So I've got some white Shengshou cubes I'd prefer in black. I'm planning on dyeing them with petroleum dye and PVC cleaner / primer. Here's the test:
People seem to think that the stickerless guhongs have less friction than the stickered ones (but are not legal in WCA competition). This might be a way of converting a stickerless guhong to stickered mode. The one thing I'm worried about is how the dye changes the friction in the cube. I should have some more information on that when I dye cubes for real perhaps this weekend. The stickerless Guhongs are made from a plastic that is so lightly colored that it seems translucent to me. So I'm sure they'll dye very easily. I've got one around here, or I lent it out. If I find it, I'll run some tests on it.
Rather than PVC cleaner, I was going to use acetone but saw a youtube video on how to use petroleum dye with PVC cleaner. An advantage is that this would put the dye into a little can complete with an applicator. It seems this makes it less likely to create a big mess: http://www.youtube.com/watch?v=1ITGM1XILb4
And there's also a youtube showing how to dye twisty puzzles using acetone, RIT dye and hot water:
But it seemed to me that it would create a mess getting rid of the dye solution, and I don't think soaking in acetone is a good idea when you have hollow puzzle pieces. The first problem is that they float so you'll have to figure out a way of holding them under water. In addition, if the pieces stick together the dye won't work. I'd rather paint on a dye in a manner similar to how you clean PVC pipe ends.
In my the video I added a lot more dye than is suggested. I suspect this may not be a good idea. If I used less dye (and more solvent), it stands to reason that the dye would penetrate deeper into the plastic. That may be a good thing. On the other hand, in some places I had to paint the dye onto the surface twice and reducing the amount of dye would make that worse.