If you go to walmart or zellers you can buy a product called Rit Dye. It is actually a clothing dye, but it works well on plastic, rubber and acrylic. I've never tryed delrin, but it would probly work. You just boil some water (use a stainless steel pot), when the water is boiling put it to simmer and add the dye, then place the bolt in the water and dye and stir it every 10-15 minutes until it is desired darkness. It does take a while, probly at least 1-2 hours to soak in. After it is dyed, you rinse it in COLD water. Some of the color will wash off, but most of it won't. If it is still not dark enough, put it back in the pot for longer. You have to be careful not to make a mess, the stuff stains pretty good! Keep a spray bottle of bleech/water to clean up spills. This is how I dyed my pump parts purple. Hope that helps!!

My hubby has a Lasoya promaster too, he has the same white bolt! lol.