I've wanted to build something that makes a Raspberry Pi "inaccessible" for a long time. I work at resin.io where we make it possible to safely deploy and update code on embedded devices "in the field" where you might not have direct physical access to them. If you can't easily get to it if you mess up a deployment or update, then it becomes really important not to "brick" a device!

It finally occurred to me that what could be more inaccessible and "embedded" than being actually embedded in clear epoxy? A rock hard brick of resin with a computer in the middle of it is about as inaccessible as you can get!

I did a lot of research up front on different materials, trying to find what was clear and safe to use on electronics. Finding something truly clear was the first challenge until I found the magic phrase "water clear epoxy". Apparently it's "water clear" that means "really actually clear and not just kinda translucent" if you're in the materials business.

Once there I started looking for materials that were safe to encase (or "pot") electronics. They existed but they were all very expensive and would cost me in the neighborhood of $150 or more to encase a single Raspberry Pi. On the other hand, there were plenty of materials intended for covering counter and table tops that would cost me $15-20. So I decided to start there and see what happened.

The interesting bits I learned at this phase are:

• There are a lot of types of resins and epoxies out there. Some of them shrink when they dry and some get extremely hot while they set up.
• Fortunately, most of the cheapest epoxies are also the ones that don't put out much heat and don't shrink too badly. Epoxies intended for home use are best (and also don't put out a terrible odor).
• "Water clear" is the magic phrase to find clear epoxy.
• Clear epoxy is not electrically conductive but is a good conductor of heat, so it's great for electronics.