Mnt reform laptop. The left trackball button is black and looks a bit rough. https://tooting.ch/system/media_attachments/files/110/419/525/866/507/765/original/cb257201cd3723ed.jpg
After @jacqueline told me it was possible, I tried 3d fdm printing a keycap for my mnt reform trackball. Went surprisingly well!Getting it to fit was a bit fiddly and not the sort of process I enjoy, but it sure beats not having just the exposed switch...