Not so sound stupid or anything, but can you bake/burn the plastic enough in an oven at 120F for like 10 minutes to make them black, then dyesub? Either way I still think it is doable, unless you have bad equipment. (yes, ignoring inhuman perceivable contrast).
Yes me wants portal man single keycaps, pbt fine. Companion cube, aperture science, gun marker, & PotatOS. I think I will need to make the pinkie pie portal-man. give me a few.
Yes, I is a noob as you can tell.
opinion: black > white. white hurts my weary eyes. Blacks helps me concentrate on my work.
EDIT: made mistakes, learn you guys are talking about dyesubing. Thanks Djuzuh, this one knows this, still it blinds me more. But about the oven thing, depends on the plastic. (of course pure black is not in my keycaps).