soooo I don't know if this is even possible within the framework you are using but the sheer math screams inventory cap at 999 rather than 99.
It take 6 flax fibers to make 1 thread, it takes 6 thread to make 1 cloth, it takes 3 cloth to make a cape(might have been another item but i think it was a cape). 6x6x3 fibers or 108. You literally can not hold enough raw materials to make 1 piece of relatively simple clothing. Additionally, it kinda sucks that we seem to lose any extra we gather. The only options I can see to really address this annoying situation are to either expand the inventory or provide some sort of alternate storage, preferably both.