[Trexmaster]

When crafting Leather Knuckles and Silk Strings (and any other weapon part that demands a specific ore/cloth/wood id imagine), you still have to choose a material to start crafting it, but it still takes the material listed (Leather Knuckles still consume 5 Leather Squares, no matter what material you pick to start crafting it, same with Silk String and Pureprint).