Blank keycaps and 3D sublimation

How can I make APL keyboard?

There were many APL keyboards in the past. There was even APL portable machine. These are definitely cute, but too hard to DIY. So I've decided to imitate IBM's PC keyboard. The keyboard is common PC keyboard, but keycaps' legends indicate APL symbols. Now my problem is:

1. Get blank keycaps.

2. Print legends on them.

3. Swap the keycaps for common keyboard's common keycaps.
Easy, isn't it?

You can buy blank keycaps at WASD Keyboards. If you are patient enough, not finicky and ready to pay much, you may order printing to WASD Keyboards. But I'm impatient, finicky, mean and love DIY.

How can I print legends on blank keycaps? Keycap is complex three-dimensional object.

After a long long googling, I've got the conclusion: 3D sublimation.

Dye sublimation for T shirt is in common use. You prepare a inkjet printer, swap the ink for dye-sub ink, print on dye-sub paper and transfer the ink to T shirt by iron. 3D sublimation apples this technology for curved surface. It uses thermoplastic film instead of paper, vacuum-former with heater instead of iron.

What I need is:

1. Inkjet printer.

2. Dye-sub ink.

3. Thermoplastic film for 3D sublimation.

4. Vacuum-former with heater.

1, 2 and 3 sell at Aliexpress. 4 is the name of the game.