Hardware is hard.

Why, oh why, didn’t we start a software company!?!

It was the fall of 2011. We were trying to build smartphone apps that would replace the loyalty cards at your favorite local retailers. We had a problem: every retailer we signed up had a different point of sale system, and we were having to write custom integrations to get our software to play nicely with potentially thousands of systems. We had to pick the problem we wanted to solve: spend the next few years reverse engineering cash registers, or build our own “thing” to do our job for us.

We built a thing

Our first prototype was milled out of a solid block of aluminum. It weighed over a pound. If the terminator robot had somehow mated with a lego brick, this thing would have been the spawn.

But our hunk of metal held a cool trick up its sleeve. When you pressed it to the screen of a smartphone, the phone would detect the five nubs that extended from the bottom in the same way it detected human fingertips.

Those metal “fingers” were in a unique configuration on each and every stamp. We wrote an iOS app that would detect the locations of the metal fingers and run the resultant coordinates through an algorithm. The result is that this app would know which of our stamps was touching it — without using any sort of wireless antenna or radio.

We started showing our invention to our friends at other startups, and they got excited. The SnowShoe Stamp was a new way to interact with smartphones.

One word: plastics

The stamp may have been a new way to interact with smartphones, but it was far from ready for commercialization. The aluminum stamps were bulky and expensive. Luckily in the summer of 2012, we won a Makerbot 3D printer at the TechCrunch Disrupt hackathon in San Francisco.

We quickly started looking into conductive filaments for that machine, and, by the winter of 2013, we were able to print fully functional stamps out of conductive ABS plastic.

The aluminum stamps had been costing us about $25 each to manufacture. Our makerbot only used about $0.25 of plastic to make a stamp.

The great cover-up

While plastic stamps were far less expensive to manufacture, they still had a fatal flaw. The conductive touch points that the phone would report as “fingertips” were still exposed — out there for the world to see.

After a lot of trial and error, we came up with a solution to this problem. Our 3D printers were capable of “dual-extruding” plastic. This means that they can print two different plastics on each layer of the print.

We loaded up two plastics: one that was conductive, and one that wasn’t. This allowed us to print a solid rectangular cube of the non-conductive plastic that had our conductive touch points embedded within. With this one innovation, the SnowShoe Stamp went from “oh, I see how it works. That is neat!” to “OMG, how did you do that?”.

While it has changed significantly over time, the stamp has evolved into a very clever piece of plastic that can solve a ton of huge problems. Physical:digital is a real painpoint right now and SnowShoe’s technology may well be the very best option to address this issue. We are psyched.


The state of the stamp

Hardware is still hard.


We have made our hardware prettier, more functional and less expensive to manufacture. However, we are still a long way from having hardware that lives up to our own standards of design, quality and scalability.

We are still making all of our hardware on a farm of 16 3D printers. When the printers are running well, we can only make about 5000 stamps per month. Unfortunately, the printers do not often run well.

It has been very hard to determine exactly how much effort we should put into the 3D printing process. We know that we need to shift to a far more scalable manufacturing system, and we are currently investing significantly in the mechanical engineering and material science necessary to get us there. If our process stays on the rails, by the fall of 2015, we should be spinning up capacity to manufacture hundreds of thousands of stamps each month through our network of contract manufacturers

This means that the total lifetime of our 3D printing process is limited, and any investments in that process and infrastructure need to be justified by short-term returns. We are trying to strike a balance between supporting our early customers in the short term, and maximizing returns from our manufacturing investments over the long run.

Today’s problems

Our hardware holds the tantalizing promise that it is the one physical:digital technology that is both easy to use and works on every mobile device. A few months ago, some of our users started reporting erratic failures on a plethora of Android phones and tablets.

While we were quickly able to replicate the failures, their cause was excruciatingly elusive. One stamp would work great on most devices, but fail on just one or two. The next stamp off the line would fail on everything except the one or two that worked for the previous iterations.

We followed several dead ends. Sanding the stamps would make some of the bad ones more reliable in our tests. The logical conclusion? The bottom of the stamp must not be flat enough. We scaled up the ability to sand the bottom of every stamp we made, but our customers continued to report erratic failures.

Cause and effect

About four weeks ago, we finally isolated the cause of these failures: conductivity. It turns out the conductive plastic we are using in our 3D printers is, on average, just barely conductive enough to allow most stamps to work on most android devices.

The problem is that feedstock is inconsistent. (Caution: nerd speak incoming) The resistance per foot can vary by three orders of magnitude within a single spool of filament. This explains why one stamp coming off an individual printer might work, but the next one doesn’t.

This discovery sparked a quest to find better plastic feedstocks for our printers. A quest that is in-progress, and, yet, to date has not yielded a short-term solution: none of the filaments we have tested both print reliably and are conductive enough to solve our Android reliability problems.

The path forward

The good news about our current sourcing conundrum is that it should not have any impact on our ability to mass-produce stamps that work on all mobile devices. When you are making hundred of thousands of “things” each month, you get to specify the exact chemical composition of your feedstock.

Until that scaled manufacturing process comes online, however, we are forced to make do with 3D printing all of our hardware. Right now, our stamps work really well all the time on iOS, and work really well on some android devices some of the time.

We are actively scouring the world for 3D printer filament that is both consistent and conductive enough to satisfy our needs. If we find it, we will see a dramatic increase in the reliability of our hardware when used on android devices. Until/unless we find that magic plastic, we are forced to limit our claims — for the time being, our stamps are only guaranteed to work on iOS devices.

SnowShoe has raised over $3.5 Million from some of the best investors in the world. We have been fortunate enough to be accepted into two of the most exclusive accelerators in the US. We have some amazing clients and, as of April 22nd, 2015, 2730 people have ordered one of our developer kits and they have built 986 applications.

We know we are extremely fortunate to be surrounded by this community, and at a bare minimum, we owe it to this community to fulfill the promises and claims we make to them. We are doing everything we can to fulfill and surpass our promises, and, in the meantime, we simply ask for your understanding and patience. Hardware is hard.

SnowShoe Stamp is a startup located in San Francisco, California. We make plastic stamps that unlock the digital world through a simple touch on your mobile device screen. Click here to learn more about how our stamps work.