Epoxy nut ?

Hi all,

I have a garage door opener with a nice 8 foot multi-start screw.

I want to make a nut for in and instead of trying to cut the screw to
make it into a tap, I would like to make a form and fill in epoxy.

Any suggestions what epoxy would wear well ?

And any suggestions on a release agent ? I was thinking silicone
spray, but not sure if that is the best.

I figure I would be safe by casting this on one end were there is no wear.

Dave