I Built a Thing! (Almost) – More Adventures in Interning

I measured my best foam model for the input module and transferred the measurements onto a block of wood. I cut and sanded the wood until it matched the foam model.

I split the model where I wanted my two vacuum-formed pieces to join. I made an intake seam around the outside of the bottom half, with the hopes of it creating a ridge in the form, that I could then use to assist me in joining the two pieces. I wasn’t sure if it would work, but hey, that’s what prototypes are for!

Hot tip for my future self: wait for shellac to cure completely before vacuum forming over it. Don’t rush. Don’t be dumb. Just be patient.

I used scrap 3mm styrene that the workshop happened to have lying around for the top half because it was free. When it was time to do the bottom half in a translucent plastic, I had to purchase material. My workshop advisor recommended I use a thin, flexible material so that it would hug the intake seams better. I ended up buying 1.5mm PEFG, which obviously created a discrepancy in size between the two halves. No regrets, It was good to experiment between the two so I can evaluate the benefits of both.

Next I just had to cut in holes for the mechanical elements and trim the edges.

The differing sizes between the two materials threw my joining plans out the window, so i milled an inner rim on the top half so that the bottom half could tuck inside it.

In other wonderful news, I need to create 3D printed objects for one of my uni assignments!


So naturally, I’ve embraced the crossover potential.

After getting this far, I thought it was high-time I get all my thoughts and processes into a readable, repeatable document. I measured and modelled what I had and learnt whether the technical package was going to work as I expected.

With the finished CAD model, I was able to look at what was missing. I still needed to add the flourish of the StemTap logo around the dial. I also needed to find a way to indicate where the user was meant to tap the unit to initiate connection with the commander module.

Thinking retrospectively is not always a great idea, but I decided bead-blasting would be a cool way to frost the clear plastic, give a grippier texture, protect it from scratching, while also creating a visual signpost.

I tested a piece of similar plastic (acrylic) by masking it and blasting it. I checked the effect by peeling back a strip of tape one at a time and seeing how far I should go.

The bead-blaster knocked the masking tape around enough to give it an unintentional rough edge. The workshop advisors have told me about laser-cut tape which can avoid this problem and the Stemtap guys thought a vinyl cutter could help too. I can’t wait to learn more about these options and see how they work.

I think the acrylic was more successful than the PEFG. It came out with zero colour alterations. The PEFG was also still scratchable after blasting, whereas the acrylic was much tougher.


We’ve all learnt a lot through this process and have lots of ideas for further iterations, but as an initial working prototype for testing, this is a good start.

Once the technical package has been produced, I’ll work on building the internal scaffolding and joinery. For now, I’m moving onto the other module!

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