I don't think You will be replacing Your original keycaps with these any time soon, but they are still a cool option for some customization and are perfect for some kind of keyboard switch fidget toy, like the Swidget, which these keycaps were actually designed for.

Tested with Gateron Low-Profile V2 switches and they fitted and were as stable as original double-shot PBT keycaps I have.

In slicer It's really important to set “Detect narrow internal solid infill” to “false”, because it messes top surfaces up, when You have any legends added.

This design is parametric, so You can customize it further yourself using OpenSCAD or even online with MakerWorld Parametric Model Maker
Simply click "Customize" on the design's page and You can customize it however if fits You.

How to set up keycap with a colored legend:

• generate and download both keycap and legend from Parametric Model Maker
• open main object (`uniform keycap low-profile.stl`) in the slicer
• right click on the object → Add modifier → Load…
  
• select file You want to add
• change filament for that object by pressing keyboard key corresponding to the AMS slot number.
   

If You have any ideas or suggestions - feel free to contact me.