Lots have been written about the Delrin DIY nut by boring and melting it around the acme screw. The problem most, including myself, experience is that the nut comes out very tight and reheating and rolling up and down does not help. I found a solution that seems to address this issue and will let you know how it works out in a long run:

Spray part of the screw with a primer or something else that will provide a thin uniform layer and make sure it dries for at least 24 hours. Then, reheat the screw few inches from the painted area and thread the Delrin nut so that it goes over the hot portion first and then force it over the painted area to cool down. After cooling down you will have to wrestle it off but the nut seems to move freely after that while maintaining zero backlash properties.

Good luck.