This is a toy called "Pyramis" made by Haba. The blocks have holes in them, and there are cylinders that fit into each hole, so they all nestle into each other. It's very neat. Three doesn't quite "get it" yet, but he enjoys working with it and exploring different ways to fit them together.
Another idea from No Time For Flash Cards (seriously, I love that site!). Three is not a fan of getting his hands messy, so actually getting him to fingerpaint was tough. Although, since then he has asked repeatedly to finger paint, so that's progress!
I was nursing Four, and working with One on her schoolwork when Three painted the fish (using a rolling pin covered in bubble wrap for a neat texture). Daddy and Two were helping. So, I didn't get a picture of the actual painting, but here are the painted fish, and some I had already cut out.
And, the final product: