I saw something the other day you might be interested in doing. My wife dragged me (kicking and screaming, I might add) into the local Wild Birds Unlimited store. An artist had some wooden artwork there, of birds. He/She had cut birds out of wood, and had pieced them together out of different kinds of wood (For instance, there was a bluebird, on a tree branch. The bird was pieced together out of different kinds of wood. The head was out of one piece of wood, the wings were made out of different kinds of wood, the body and tail were different kinds of wood, all pieced together). That would be a dandy project for you to try in different colored plexiglass. Complex but easy shapes that fit together to form a bird. I'll see if I can find you a pic of what I'm talking about, but I think you get the gist.
Gunner