The Rigid strips are basically the flex strips, just cut into smaller pieces and then stuck on an aluminum track, so really you can do exactly the same things with both, and the flexible strips just give you more options. I guess there would be designs were the the rigid strips would be less of a hassle, no cutting and already attached to something to hold them straight. I haven't decided which direction to go with mine yet, so it really all depends on the exact project you are going to use them in.