The parts are made of clear polycarbonate, which was also used for the originals, I think. They are very sturdy and apparently have good thermal tolerances.

The colors are: red, blue, green, amber, smoke, clear, and solid non-translucent black. Clear and black will cost less, since they are easier to make, and to allow for guilt-free modifications.

A note, though: The knobs are VERY tight. I have taken the MKIIa knob on and off my player a few times and it seems to have loosened, but it's still really tight. It will be very hard to make the shaft bigger in the mold, so I'm inclined to leave it over-tight. Two slots could always be cut into the shaft (like the original) to let it expand, and the spring could be uses to hold that together. I think it will work out.

And the MKII knobs seem over-tight also, but I don't (yet) have an MKII to test them on. I'll try to retrieve the encoder I lent my molders.