For the dark brown issue, is it related to the temp or the timing?
I'm not gonna spend 1000+ euros.
To keep the cost low, I'm thinking to order dye-sub printed paper from some printing companies. (probably several usd/euros per sheet)
Some previous posts mentioned thermal conductive silicone pad, which can be good for the curved surface of keycaps.
And, I might use a heating element from aliexpress, or just a home iron.
The confusing part is, whether I use heating element -> silicone pad -> dye-sub paper with proper ink -> keycap , but without a special dye-sub coating.
Some say that a dye-sub coating is required. But, maybe the coating is required for smooth surface, like ceramic cups?