One part has two colors？

[N. W. Perry]

If some colors of this part are fixed and some colors can be modified in "studio", how can I do it?

The portions that are modifiable should be given the color 16, and those that are fixed should get the appropriate code for the color (0 for black, 15 for white, and so on). Color 16 basically means "whatever color the user assigns to it".

For modifiable portions that are lines/edges, use color 24 instead of color 16.