Chopper is an Astromech, just an older one. His designation in Star Wars Rebels is C1-10P. He's the crew's resident grumpy old droid.
At this point my project is about 6-7 years old. I've learned a lot and have greatly enjoyed my time with Chopper. It's been very rewarding entertaining both kids and adults who also love the droid.
Since building BT-1 I've wanted to upgrade Chopper with everything I learned. As soon as I don't have any conventions lined up I hope to upgrade the wiring, emergency cutoff switch, and some of the minor cosmetic details. Chop's skins are styrene and you can imagine over the many events we've done they are cracked and broken in some places. I hope to patch and repair instead of completely replacing his skins. He desperately needs a new rear door. It's falling to pieces.
That's an awesome Chopper. I'm looking at making one... do you have leg STL?