Is truck bed liner still the go-to for Glock reduction/stipple?

[anachronism]

Hmmm... I wonder how the stuff sold for repairing plastic radiators would work. The stuff is really tough, but seems unsuitable for repairing cracks in plastic tanks.

[Surf]

You need to think along the lines of how people add texture to synthetic stocks on rifles.

Or you could go old school and break out some checkering files.

[sammage]

Op you're thinking off something more like using Marine-Tex.

http://rdprecision.net/do-it-yourself-stock-texture/