Duppa I2C MIDI Controller 3D Print Case

By Kevin on April 27, 2025

This is a simple 3D printed case for my Duppa I2C MIDI Controller PCB.

Warning! I strongly recommend using old or second hand equipment for your experiments. I am not responsible for any damage to expensive instruments!

If you are new to microcontrollers, see the Getting Started pages.

Parts list

Duppa I2C MIDI Controller
USB-C lead or serial MIDI.
MIDI device

OpenSCAD Design

This uses some of the techniques from my Raspberry Pi 2,3,4 A+/B+ Synth Cases to define a basic box, then some cut-outs, and then to split the box and add some overlapping "lips" for a snap-fit.

There a number of functions to achieve this, but some of them are just collecting together the others in the right sequence.

rounded - a basic "rounded" box module.
standoff - the PCB supports.
build_lips/build_lip - as expected, creates the overlapping lips. There is a parameter (solid) which determines if the lip is added to or subtracted from the case.
base - the main box shape, less the actual top.
top - the top plate that includes holes for the potentiometer and the LED ring.
box - uses base() and top() to build a complete box.
box_base/box_top - uses box and an intersection to produce the two halves of the main box.

At the top level box_base, box_top and standoff (four times) actually builds the complete case.

In terms of assumptions about the build:

Most importantly, this assumes the use of PH5.0 headers to mount the Waveshare Zero device.
It also assumes the use of a serial MIDI TRS socket.
It should allow for M3 spaces and is build to assume two sets of 10mm spacers as described in the Build Guide.

Errata/Improvements:

For my own build, the potentiometer shaft doesn't stick out as much as I'd like. It is hard to find a knob that doesn't have to be altered to fit and stay in place.
I did wonder about using a thinner layer of 3D print over the LEDs rather than complete holes. I might still try that as an option to see how it works.

Find it on GitHub here.

Closing Thoughts

This is a little tall, but I'm not sure what, in reality I could do about that. There might be some option for shrinking it a little, especially if the Waveshare Zero RP2040 is soldered directly to the PCB. But it would only save, maybe up to 6 mm in height, so it is probably not worth the effort.

But apart from that, this seems to have come out really well. The holes the LEDs I thought were perhaps a bit of a compromise, but actually they seem to work fine.

Kevin