Not a stash builder here. I buy for projects only for the following reasons...1) no place to store a stash; 2) not into 'scrappy'. That said, I do 'over buy' a bit when purchasing. If the pattern calls for say 1.5 yds, I'll get 2, etc. This gives me enough for mistakes and a bit left over. Then, when doing another project and I only need a small amount of something, I have a clue as to if I need to purchase that particular piece. I don't cut leftovers. I leave them in the state they end up when I'm done. I will even keep scraps - both large and small, so if I want to figure out something or am doing a pp'ing block, I have things to work with.