Hey! Really enjoyed the textural changes as you went from variation to variation! Compositionally, I think I would have liked a change in harmonies. The progression Dm-C got repetitive after a while. Even if you transposed it up to Gm-F at key moments, that would help build energy and momentum into another section/variation.

This piece is like: A-A’-A’’-A’’’-A’’’’ etc etc….
You could try: AABA-A’A’BA’-A’’A’’BA’’ etc etc…. or some kind of variation on this, that adds a harmonic change… That would have made this more interesting for me at least. Does that make sense?

Still, good job on keeping the variations changing with different textures and instruments. If you were purposefully keeping yourself within that harmonic progression, that's really difficult to do...so nice one!

Neato. Cool work.