Over the course of the past year, I’ve been working towards turning turning a Psion Series 5 keyboard into a practical, day-to-day, Bluetooth keyboard. In my previous two posts on this topic, I described making the Psion Series 5 keyboard function as a Bluetooth keyboard, and producing a custom printed circuit board to reduce the size. The next step is to create a minimal case to hold everything together.

The Psion Series 5 keyboard itself comes as a complete component and, if possible, I’d like to reuse as much as I can, fabricating a case that holds this part, along with the battery and electronics. As a reminder, the completed keyboard electronics—including the keyboard component itself—look like this:

Psion Series 5 keyboard

I’ve been using Autodesk Fusion 360 to model the case, and ultimately plan to use Shapeways for the 3D printing as I was impressed with the finish of the Nintendo 3DS Cartridge I had printed in ‘Strong & Flexible Plastic’.

Grand Ideas

I had originally hoped that the Psion keyboard would contain individual component parts I could reuse, allowing me to design a completely custom case: an angular, modern, departure from the 90s curves of the Series 5. Upon disassembling the keyboard however, I discovered the outer case forms a key part of the keyboard itself:

As you can see from the photos of the four layers, the keys mount directly onto the case itself, saving on parts and space. This means that, in order replace the case, I would also need to design my own mounting for the keys.

I tried designing my own mounting for a single key for this purpose (leaning heavily on the Maker’s Muse YouTube channel for an introduction to Fusion 360 and tools like contraints:

Key mount

Unfortunately, the dimensions and tolerances here are so tight that I’ve little confidence I’d be able to produce a good key action, and ultimately Shapeways' rejected it as unprintable due to thin walls and overhangs.

A Simpler Approach

I soon realised that attempting to design the whole keyboard (mounting and all) myself was too much to bite off, especially given my limited Fusion 360 experience. Instead, I decided to explore ways to design a case which integrated the whole keyboard component from the Psion:

Basic Design

If you can make any sense out of my sketch, you’ll see that the goal is to 3D print the vertical walls of the case, and have the existing keyboard component sit on these. The hinges–originally intended to join the keyboard and screen–can be reused to anchor the keyboard to the new case:



Many more sketches, projections, and Boolean operations later, I have a model like this:

I couldn’t resist the urge to play around with three.js to display my STL files.


To save me from dropping lots of money on 3D printing–a print of this size costs $60 a time from Shapeways–my colleague Jeff very kindly offered to print some of the early prototypes on his Ultimaker 3:


First print under way

As you can see from the photo, the keyboard is pulling away from the glass plate very slightly towards the right of the print. Apparently this is due to the plate not being warm enough to keep the PLA adhered to the plate.

The printing process was a lengthy one, and I’m extremely grateful to Jeff for his patience. Both the childlike wonder that such things are possible, and the realisation that there’s still a long way to go.

Iterating the Circuit Board

Over the course the case design, I’ve realised that I need to tweak the circuit board design to reduce the vertical space, and ensure that the charging port and power switch are well placed along the back edge.

Next Steps

Nearing Completion

Nearing completion

After many prints, and design tweaks–both to the case, and circuit board–I feel I’m finally converging on a functional design.