Category Archives: Tech

How to Build it: Lean Prototyping Techniques for Hardware

I recently wrote on my vision for the future of 3D printers, largely on their use for manufacturing.  I wanted to expand more broadly on my thoughts on prototyping technologies, and particularly for rapid and lean prototyping for mechanical designs.

“Lean” started in the context of manufacturing automobiles, and has since been taken to describe prototyping and customer development for software start-ups.  Many software/web start-ups do not win because of a science or technology invention.  Instead, user experiences and marketing are what drive success.  I think people are realizing that this can apply for hardware as well, and the increasing ease of prototyping is helping to drive the increase in hardware based projects and start-ups such as those seen on Kickstarter’s design section.  Of course, hardware continues to have the challenge that production and distribution continues to be more difficult than for software.

I will outline here tools and methods I use in prototyping hardware.  What do you do? (please post in the comment field below)

The Dollar Store

Duct tape, super glue, spray paint, and a dollar store full of imagination are possibly the best (and maybe least expected) prototyping tools.  I’m a strong advocate of the super-alpha prototype: the more you can build quickly, the faster you can find what you don’t know.  It’s also easier to get excited about a project when you have something tangible to show people (potential customers!)

Don’t forget the spray paint!  A prototype that looks sketchy automatically throws off people you show it to.  Civilians will discount even the best features on a prototype if it looks unprofessional, unfinished, and ugly.

Amazon, electronics stores, and hardware stores are also great resources, especially once you have enough of an idea what you are building so that you can specify a specific part.  Before that, quick, cheap, and convenient should be the main criteria for finding parts and materials.

Pen and Paper

Very quick calculations can prove your idea violates the laws of physics.  Save yourself embarrassment and make sure that you are the one to do these calculations, not someone else (like an investor) and that you do them before you invest too much time into a project.  Such calculations can also help decide between design alternatives and optimize design choices.

Simple sketches can help realize ideas and form them to guide physical prototypes.  There is often a lot of different ways to build or do something.  Having different ways on paper can help deciding which direction to take.  They can also express your ideas quickly to other people.

Computer Modeling

CAD Model and Development, Image courtesy Nikola LK

A tried-and-true method for professional mechanical designers, some computer aided design (CAD) programs have come down in price a lot recently.  Alibre for instance is about the same price as Microsoft Office Home and Business, and gives probably 70-80% of the functionality of professional design software.  Entry-level CAD systems often don’t have simulation applications to test the physics of parts, but some packages are available open source that do.  Simulation also requires training to do make reliable models.

I’m not sure why CAD isn’t getting more publicity for maker, hacker, and hobbyist use – a physical model is often easy to make from a fully rendered CAD model. CAD models can be changed easier, quicker, and at less cost.  Design iteration time on CAD can be as quick as modifying software code.

However, if the final widget uses parts that interact with one another, a CAD model may not be able to prove everything works together.  This is especially true for moving parts or imbedded electronics.

2D Cutting

75mm thick steel, cut by waterjet, Image courtesy Fromthecorner

Waterjet and laser cutters etch or remove a pattern from sheet metal (and other materials).  The sheet can then be folded to a 3D final shape.  These can be very cheap and quick: for example a small part could be made in as little as five minutes and at a cost of $5.  The size of the machines makes them practical for anything from smartphone to laptop size, with exceptions either way for certain applications.

The machines are not common in people’s houses, and take a bit of a different design approach: you have to think about your 3D project on a 2D sheet.  Even if you don’t have one in your house, there should be several companies that will be able to cut your part in even a small city.

Additive Manufacturing

The fancy name for “3D printing”, additive manufacturing has become popular for hobbyists and the media.  It is fascinating to watch a part grow in front of you, and a variety of metals, plastics, and rubber-like materials are available, but generally not on the same machine.  Machines are also now small, cheap, and usable enough that they are no longer restricted to industrial use.  Assemblies that would otherwise require serveral components can be built as a single part on a 3D printer.  3D printers allow for making parts that are impossible with other processes, for instance parts with internal holes and voids.  They also can be used to make quick, inexpensive tooling for molds to make parts from.  A prototype can be made for $20-$100+ depending what it is.


Computer numeric control (CNC) usually refers to a milling machine that cuts a big chunk of metal (or other material) into a finished part.  It was probably the first type of “prototyping machine”, but is often used for production as well.  Usually people don’t have these in their house (although the hobbyist and homemade CNC group seems to be growing), and CNC parts can be more expensive than other contracted parts.  Usually parts are in the $150+ range.

Molding and Fibreglass

Carbon fibre aeroshell from a fibreglass mold, UBC Solar Car team

Molding and fibreglass are great for making irregular-shaped parts or if you need several copies of the same part.  There can be a lot more initial work to make a mold than other processes, but quick molds using hobbyist and film-industry materials can be made pretty quickly.  Some chemicals involved in fibreglass and some molds are toxic and require gloves and/or ventilation.  Materials can be quite cheap, $50-$100 is enough to make most small-medium sized parts.


Welding allows the joining of metal.  It is useful for many different parts including frames from metal tubes or making sheet metal into 3D parts.  Like molding, there can be a lot of set-up time in making jigs to hold parts in place when they are being welded.  Spot welders are good for quickly joining metal pieces and require much less skill to operate, and are particularly useful in joining 2D sheet metal projects that were cut on waterjet or laser to make 3D parts.  Often, glues are easier to use and will suffice for a prototype.


Arduino and other microcontrollers are an easy and cheap way to prototype and integrate electronics into a project.  There are lots of examples and support for the platform: someone else has probably already solved the problem you are having and is willing to help. Sparkfun and others have good sensors and other electrical accessories that work with Arduino and other platforms.

User Feedback

If making something for more than a few people to use, you have to talk to people you hope will use it.  Live demos or letting potential users play with your prototypes is important.  But it’s also important in who you pick to ask for feedback and how you let them use it.  With this feedback, you build improve the next round of prototypes, until the project is ready.  I expect there are many parallels to Lean software development here.

How I (try to) pick people for feedback:

Open to Change

Don’t take away Milton’s stapler, Image courtesy Devinpoore

If someone is too happy with what they already have, they will be resistant to change.  Even worse is if the user doesn’t want to change but they think their boss will force them to.  These types of people will think of any reason your prototype won’t work, and it can be tough to convince them differently.  Try to take away Milton’s stapler and he’ll burn the place down (reference to the movie Office Space).

Will Give a Fair Assessment

Like the above person who will only say negative things about your work, try to avoid people who will only say positive things.  Your mother is not the person to get good feedback from, assuming she is supportive of everything you do.

Some people get excited about anything just for being new.  Feedback from them can be motivating but may require coaching and interpreting to make the advice constructive.

Is Sympathetic to How Prototypes Are

Prototype for a hovercraft, Image courtesy Timothyrfries

Many people are never exposed to how things are made.  Stuff comes from Amazon or Walmart, and it better be perfect.  If it breaks, looks ugly, sounds funny, or crashes, it’s a bad product and the company that made it may never be trusted again.  Unfortunately for people looking for feedback, I expect most people fall into this category.

These people need to have their hands held if you choose them for product feedback, as they are often disappointed with what you show them. You need to manage expectations and teach them what exactly your prototype is showing.  If they understand the prototype is only testing a few features of a final product, they will be more understanding.  These people are why spray paint and making your prototype look good is so important: for early stage design, discussion should be about ideas and features, not distracted by aesthetics.


Prototyping is cheaper and easier than ever.  In my opinion, a prototype for many Kickstarter-ready design projects could be made for $1000 in parts and materials, some for even $100.  Like software development, the larger investment is in time put in by the designers. Of course, several (or sometimes many) stages of prototypes are needed to arrive at a final design.  Good user feedback is essential, and this feedback should guide making the next round of prototypes.  It is an iterative cycle.  The key to making good products is making mistakes early and learning from them.  This is best done through prototyping and getting user feedback.


Many of my ideas and views on prototyping were formed in the University of British Columbia Mechanical Engineering program, and particularly from the design faculty.  Some thoughts are inspired by work from the Center for Design Research group at Stanford and the Engineering Design Centre at Cambridge.  Any of these three groups are great places to look more in-depth on these points.



Start of some good discussion on HackerNews:

Perspective on 3D printers from a mechanical designer

3D printed part that would be (extremely) difficult to make another way. Photo credit: Axel Hindemith Lizenz: Creative Commons CC-by-sa-3.0 de

This is in part motivated by Jon Evan’s recent article on TechCrunch ( but more to add to the discussion of new manufacturing technologies from my experiences that have been brewing for a while.  I agree with Evan’s thesis that 3D printing is alike 2D printing only in name, but my experience is that 3D printing are a great tool, but will not be a total revolution in manufacturing as some suggest.

I am starting a PhD in Mechanical Engineering soon and have been using 3D printers, waterjet machines, and laser micromachines for three or four years now on a prototyping basis.  I am writing this mainly directed for the software tech crowd that has recently become more interested in hardware.  Some of my conclusions:

1. We will not see 3D printers in everyone’s home

I don’t see 3D printing as being a new fixture in everyone’s home.  This is because 3D printing:

  1. requires design input, which requires developed skill and time
  2. is a slow process, and
  3. materials are (currently) poor quality from an engineering perspective

I do see growth in residential use, but only by the same kinds of people who have a wood working shop and welder in their garage, or who do I/O software or robotics projects. They are a nice cross-over between software and hardware.

3D printing needs design input, and for more than the most trivial parts, this requires computer aided design software and the skill to use it.  It’s far more work than most people are willing to invest.  If you are just going to make parts of other people’s designs, why not just outsource the production to them as well?

3D printing is slow, with even small parts taking hours to make.  Unless it’s a custom part (that you’ve designed yourself), its much quicker (and cheaper) to find something off the shelf.

3D printing materials are apparently better than they used to be, but I still find they crack often and easier than would be acceptable in most uses.  Yes, there are examples of parts that are made by 3D printing that work fine for their use, but a molded, casted, or machined part will be stronger.

2. 3D printing will not revolutionize manufacturing

For the same reasons listed above, 3D printing is not a great production technology.  But, more importantly, the economies of 3D printing are only efficient below about 10-20 parts.  After that, casting or injection molding is typically cheaper, except in a few cases I will discuss later.  At large volumes, the per-unit cost of a plastic part in injection molding could be well under a dollar, and the same part in 3D printing could be over $100.  The exception is where 3D printing is making a part that is “impossible” by other methods or that would require multiple parts and assembly.

 3. 3D printing is good for prototyping and one-offs (but not the only way)

For doing something once, whether for prototyping or if you only need one, 3D printers can be a great tool.  One cool application is surgical planning or even custom implants by 3D printing (such as  And it makes sense because everyone is different enough to justify and one-off part for them (and medical device costs are high enough to allow it).  But replace overseas injection-molded parts with a 3D printer in your garage?  It doesn’t make sense in nearly all instances.

There are other rapid prototyping methods such as CNC waterjet cutting and laser machining that get less attention although they are, in my opinion, more useful prototyping tools.  Typically, sheet metal is cut, then folded into a 3D prototype.  These are nice because they are typically stronger than 3D printed part, are quicker, and time scales with complexity rather than size. There are also many types of 3D printers including those that “print” rubber-like materials, hard plastics, and metals.

New rapid prototyping methods are game-changing for developing new products on a shoe-string budget, and I would wager that most of the recent success stories on Kickstarter ( were developed with the help of 3D printing prototypes.  In this, the technology really does allow for cheap innovation where design is the major innovation.  I would go as far as to say these technologies are lowering the barrier-to-entry of hardware projects to a similar level as software, at least until the product goes to production.  Great news for hardware entrepreneurs!

As an aside on Kickstarter since I brought it up, it is interesting they recently banned virtual renderings of design projects.  Rapid prototyping allows for moving from virtual models to prototyped models easily, quickly, and cheaply.  The problem is that the prototypes in no way prove the company is ready to handle the demands of transitioning into production, or that the prototype has had any reliability testing.

4. 3D printers allow for making things that are impossible any other way

This is probably the second biggest advantage of 3D printers, after their usefulness in rapid prototyping.  3D printing allows for making shapes that are impossible using other methods, or require multiple parts and assembly in other methods.  3D printing in particular allows for printing parts that have irregular voids or holes that curve are very difficult to make with other methods.  Mechanical Engineering Magazine ( has had a few good articles on this over the past year, or the image I posted above is a good example.

5. 3D printing (and other rapid prototyping) machines are less reliable

3D printing and other automated machines, especially lower end ones, continue to have reliability issues.  Most of my experience is with industrial machines (costing in the $50-100k range), and even these have a crippling amount of downtime.  There are also issues that occur while parts are being built.  At best, you catch these early and can restart the part.  At worst, you come back later to find you part is a mess and the machine is damaged.  These machines typically don’t have feedback, so the machine can’t tell if its made a mistake.  Good ol’ lathes and mills, even of the CNC variety, are much more reliable.  But rapid prototype machines may improve in the future.

 6. 3D printing users need to decide between ownership and out-sourced services

3D printing machines are becoming less expensive, but still lock up a lot of capital.  For most users, their machine is probably going to spend most of its time waiting for a job, and only a fraction actually printing.  I have used a few services, my favorite is Protogenic by Spectrum Plastics (  I have found they have the best prices and have the best customer service of any vendor I’ve ever worked with.  Typically a part is delivered within 5 business days of ordering, and prices aren’t that much more than the material used in your own machine.  Therefore, the only reasons I can see for ownership of a 3D printer are:

  1. High usage
  2. Need for extremely quick turnaround times
  3. Desire for confidentiality (although most venders will agree to NDAs)
  4. Teaching CNC control theory (ie in engineering schools)
  5. To geek out

For most reading this article, this last point may be the main selling point for getting a 3D printer.  They are certainly fun and interesting toys.  And they do have niche roles in manufacturing, design, and maker culture.  But it’s time for a reality check: 3D printing is not the beginning of the end for injection molding, milling, casting, and other traditional manufacturing technologies.

Edit: there has been a vibrant discussion of this on HackerNews.  Thank you all for your thoughts and comments:

Why I got a BlackBerry

BlackBerry 8900. Photo credit: By Pizue [CC-BY-SA-3.0 (, via Wikimedia Commons

My first smartphone was an iPhone 3GS, which I bought knowingly about a month before the iPhone 4 came out. That iPhone 3GS served me well for two and a half years, including a swim in a lake, dozens of drops, and a screen replacement.  Ultimately, that abuse caught up with it, and a chocolate bar melting into the microphone finally did it in.

I am leaving the continent in a few months and a new phone without a plan discount was out of the question.  I looked at Android, but had found the platform to be at times slow and with a tendency to crash.  There are also so many phones on the platform (with similar names!) that I found it difficult to figure out which of the second-hand ones I was looking at was any good.

I thought about getting an updated iPhone.  I was used to the interface and Apple certainly makes it easier to stay with their own devices, but I’ve been turned off by some of Apple’s products forcing their choices on the user.  Using Flash should have been up to the user, not the manufacturer.  Switching to an Apple-made maps app on the newest OS was also not for the good of the user.  The iTunes interface makes it difficult to switch to another platform by making it difficult to liberate contacts and music.  I was ready for something else.

While I could say I picked Blackberry through attrition, it was actually through preference that I wanted to try the platform.  Why?


Blackberry is made by Canadian company Research in Motion (RIM), and Canada is a country with vanishingly few winning tech companies to inspire young geeks like myself.  Canada has been home to top class tech companies (Corel, Nortel, Angiotech) that all went supernova.  #1 companies can be built here, but can they continue to compete with the world?

Cheering for the underdog.

Canadians have a strong history of cheering for the underdog, so maybe this falls under patriotism.  RIM has had a tough year-plus with botched or delayed launches, a leadership change, and a stock price that values the company at only a few bucks more than the cash they have in the bank.  It would be great to see them turn things around.

Hope for the next one.

Blackberry 10 has be long hailed as what will save Blackberry, especially after the Playbook didn’t.  I’m holding hope for this, and I saw this phone has a test to get used to the Blackberry platform to see if I’d want to move to Blackberry 10 when it comes and I’d be up for a new-contract-subsidized phone.

To complete the set.

I bought a Playbook when they started selling them off at what must be near-cost, although I admit it only really sees use during travel.  While a Macbook-iPad-iPhone could be the best “package set-up”, I was hoping to see if I’d utilize my tablet more if I had a Blackberry phone.  I havet, but haven’t set up the Blackberry Bridge yet.


No, I’m not overly paranoid of the government or have items of national security in my inbox, but I do value my privacy and hope that some of ideas may one day develop into industry trade secrets.  If Blackberry’s security is enough to upset some foreign governments, I see that as a good thing.

Of course, all of these played into my decision.  I am happy with it even though setting it up as an unlocked phone was a pain, largely due to my service provider.  I find the OS stability to be better than iPhone, but the browser is slower, media player clunkier, and the maps UI isn’t as good at the old version of Apple’s. These are the major apps I use on either system. There are definately some quirks in the system (ok… bugs) and I still haven`t set up the bridge to my Playbook (after almost a month), but I`m happy with my choice. I like the physical QWERTY keyboard a lot.  Its not perfect, but I wouldn`t consider it inferior to iOS or Andriod.  I like that the system feels both secure and highly tunable, but I don’t think this tuning is intuitive or easy for most people.

This may be the heart of RIM’s problem with Blackberry: what they have built is a Hummer when most people today want a Prius. Like many, I hold hope for the Blackberry 10 to live up to its promise, and I’ll be getting one on launch day if it does.


Update: Just set up the Blackberry Bridge.  It is really cool! One issue I’ve noticed is message I read on the playbook don’t immedeately get marked as read on the handheld.