I've never used a jelly roll, so I'm only guessing. For one thing, 40 different pieces would drive me crazy (I don't do random very well -- well, not well at all.) So I'm thinking One focus fabric- a few of those, one solid, one or two blenders, and perhaps another one that would compliment the focus fabric. The number of strips divided equally. That probably sounds ridiculous to those of you who use jelly rolls for those gorgeous scrappy looking quilts.