Using most recent versions of base mod, Basic Parts, and Vender's Game available on CurseForge. Using most recent version of Forge for Minecraft 1.20.1. I am able to craft Silicate Mix and distill it into Fiberglass and Kevlar, however, when taking the Fiberglass to a Part Fabricator, I am unable to select any Fiberglass-tier product (upper/lower receivers, barrels, stocks, grips. propellers, or structural parts). This, of course, makes legitimately crafting any of the Vender's Game HitMarket guns that aren't pistols using only tier 1 materials impossible as wooden lower receivers do not exist.

I believe I fixed this in c620582
It just needs to be published to a live version