I dyed my coloured-plastic MF8 Kilominx black and applied stickers. It didn't go perfectly, but I'm very happy with the results.
I used 32g (1 box) of powdered Rit Dye Black #15 in 525 mL of water and 225 mL of acetone. This was a 30% acetone solution that, in retrospect, was probably too strong. I kept the solution in the range 40° to 50° C with a water bath surrounding the dye solution container. As this was a multi-coloured plastic puzzle, I was focused on seeing how long it would take to get a consistent colour. I kept the parts in the dye solution for 2 hours and 20 minutes. They stopped darkening after about 2 hours. In the end, I was not successful as about half of the parts are a dark-reddish-brown. The other half are jet-black. Unsurprisingly, some parts showed minor surface erosion, particularly the centres and other smooth areas. The effect on the assembled and stickered puzzle is a subtle matte mottling that goes well with the shade variation of the pieces.
Prior to this project I solved the kilominx twice without adding lubrication and with only a cursory tension adjustment. It was rough and catchy. As I reassembled the dyed puzzle, I thoroughly lubricated it and carefully set the tensions. As a result, it turns very well. I'm very happy with my dyed and stickered MF8 Kilominx.Well.. I can't seem to upload my photos (it is giving me an error)
, so here is a link
to the flickr set I made, with lots of photos and descriptions. I welcome your comments and questions.