For the M:S, you’ll probably benefit from generating them in slices that divide into 120 (so 60, 40, 30, 24, 20, …). Then you can set the length on the M:S to multiply up to 120 (2, 3, 4, 5, 6, …). I’ve had a ton of fun designing my own and composing.
Here is a little exploration of one of the SCW files I did. Basically playing around with the start length of the sample, an LFO on the filter, and adjusting the resonance by hand. I like the buzziness … kind of like a jaw harp at times, but then it can also sound like a cheap digital piano with different filter settings.