The latest prototype I am working on, code-named “infinite cart“, requires us to create a customized case. We’ve worked hard on miniaturizing the electronics – the box below contains a lot:
- A particle photon – microcontrollar with built-in Wifi for connectivity
- A Lipo Battery and charging circuit on our own custom-made PCB
- A NFC reader
- A vibration motor for haptic feedback, including the diode/transistor on our own PCB
- A neopixel strip for visual signalling
It’s so small (at least for us), that the cables within the case became an issue for the first time. Anyway, you can see why we needed to look into custom cases.
For the first 3D printed boxes we used 123D. It’s a 3D designer similar to other 2D CAD tools. While we gained some quick wins initially, one big issue became very quickly apparent: changing a tiny thing in the middle of your workflow is impossible. That means that your 3D design is a sequence of steps and only the last step can easily be changed. Sure, you can “undo” a few steps and recreate them, but it’s really painful. Below, take a look at a few designs we’ve made.
Besides the issues with flexibility, we also discovered that some 3D printing software printed the shapes in unforeseen ways. For example we added a handle to on of the boxes and it was very loosely combined with the rest of the shape. It looked like the 3D printer still thought of it as seperate shapes…
So finally, we looked into OpenSCAD. It’s a programmatic 3D design tool – so instead of working with your mouse and inaccurately sizeing some shapes on the screen, you code the 3D model. I’ve been a bit scared, because especially for “organic” designs OpenSCAD is said to be hard. So rounded corners, non-straight areas, etc. But see what we’ve made so far:
It took me an evening to undestand the basics and loose some fear, then the next day I had replicated the early prototype box. We then started working on the more organic box (see right, e.g. curved side walls, etc.) and right now we have a pretty flexible case aleady. Height, Width, Length is all customized with variables, so changing 3 numbers gives me a new design.
It turns out that this flexibility is worth a lot, at least when it comes to creating cases for prototypes/electronics.
Just a quick update, I think I’ll turn this one here into a detailed instructable just like I did with the Oktoberfest of Things Beer table. So stay tuned!