The purpose of this rig is to reduce waste while testing color combinations, number of wraps and reduction amounts. But mostly for color combos because until they are spun into a completed string, it is difficult to tell what a new combination will look like.
Start with this recipe:
12" reduced ~10% (10 3/4")
The result should yield a very short string about 4" long. It’s great for testing straightforward color blends.