The Combimouse uses ABS plastic and that is the material that 3D printers can print. The Combimouse Right Unit is a 1mm thick part.
Thin plastic parts is achievable using modern Plastic Injection Molding technology and has only become achievable in the last few years. This is suitable for mass production after a fairly expensive tool making process.
After a number of attempts as described below, I have subsequently found that it is not possible to print the Combimouse Right Unit using 3D printers. For example in this article they say “Even though you could use a minimum wall thickness of 1mm when using White, Strong & Flexible we recommend that you stick to 2mm. We would also never recommend making large portions of your model this thin because this would make it excessively delicate.”
Stereolithography with silicon moulds is an alternative option for runs of up to say 20 pieces. This costs a few thousand dollars.
For quick one offs it is best to make the Combimouse Right Unit by hand. It does take a few days, but with a limited budget and a relatively quick turnaround it is the best option during early prototyping until the design is finalised.
I attempted to print the right plastic using a 3D ┬áprinter that I had access to. I attempted to print in two orientations but they both failed. I also had limited access to the printer and so turnaround took very long - up to a week.
This printer has a resolution of 0.5mm whereas better printers can achieve 0.2mm. In addition this printer had a print area of 150mm x 150mm which is too small. So I had to print the part in three separate parts with the intention of joining them together.
So for now I will hand make the prototypes. This has a number of advantages including fast turnaround, low cost, represents what can be achieved in mass production plastic moulding and is good quality.
Initially we tried to print the part lying flat as shown here.
However it lifted on the one corner which you can see in the following photo and so we aborted the print.
We then attempted to print the part vertically. This took 8 hours.
When we removed the print from the printer a number of cracks appeared which is shown within the red ellipse in the photo below(the red ellipse is difficult to see - it is on the flat portion at the bottom.