That's great. I imagined they would weigh a ton. I didn't realize how light the materials really are. My tractors are made from an old fence we took down. I think the boards are 2 X 6, so they are sturdy but heavy. I used the boards to make 8 X 10 foot base frames, and the tops are welded kennel wire. I push the blade of a furniture dolly under one of the short sides to move them every couple of days. I like what you're doing much better.
What's the biggest one you've got?