Thermoformed round Cherry MX keycaps for multi color print or the toner transfer technique. Backlight compatible.

Note: I added a customizable OpenSCAD file for the round keycaps. 

This is my first ever attempt at OpenSCAD, so there are probably some bugs and until now no input checks. I have also a hard time naming variables, so they are not all self-explanatory. I will add a description with screenshots later.

The backlight caps that have a character with “holes”, like the 0, 4, 6, 8 and 9 produce some errors/warnings. 

For Prusaslicer:

For Cura unselect this option:

This is a round version of my square key caps that you can find here.

The keycap consists of 3 to 4 parts. 

1. The main part with the stem, 
2. the ring,
3. the inlay, and if not using the toner transfer technique,
4. the character/symbol

Thermoforming

The cap is hollow so there's room for the top that is pushed inside by the thermoforming.

To achieve the indent heat the tool you want to use (a carriage bolt for example) in hot water. For me it worked best with a temperature over 85 °C. Make sure to use protective gear to not burn yourself.

Then push the hot tool slowly into the top of the cap while slowly rotating it. It's possible that the top doesn't stay indented when you remove the tool. In this case wait a few seconds until it has cooled down a little before you remove the tool.

Toner transfer technique

See some toner transfer examples here.

Short version:

1. Print your mirrored layout onto a transparency sheet with a laser printer (make sure to use laser compatible transparencies and that the printer supports transparencies)
2. Align the transparency with the toner upwards on your 3D printers bed. For example by printing the first layer, stopping the print and aligning the layout on the transparency to the first layer. Fix it with a piece of tape on one side, and remove the first layer.
3. Drip some water (or glycerol) onto your printers bed and lower the transparency. Push the liquid out (glycerol makes a mess, but is better for longer prints) and fix the remaining 3 sides of the transparency to the bed with tape.
4. Start your print. I use a first layer height of 0.1 mm, a temperature of 220°C / 60°C and a speed of 15-20 mm/s.

Another note: The heated bed of my printer is broken, so I couldn't test all the models (I can hardly print one key cap at a time because they won't stay on the bed that long). Once I repaired it I will test every model and will also add letters.