Let me just make this a short one. Do your research first. That way you find the super helpful video that tells you what you need before you start. Let me sum up by saying I can confirm that dye alone does not color ABS plastic. Even if you let it soak all night long:
And if it does the color is terrible. I did manage to get the TARDIS in blue, tho it was too dark a shade.
You can tell what my secret ingredient is.
But now that I’ve found that video I know, 25% solution of acetone and the same dye I was using should work. If I’m lucky I may be able to offer them in my etsy store soon.