This year I decided to make a LEGO kids group costume. I used cardboard for the bodies, which I covered in joint compound. I sanded them, primed them, and spray painted them with a gloss finish. Then I painted each design by hand.
For the heads, I cut circular poster board, and wrapped it around with a thick poster paper for the face. The mouths were cut out as eye holes and covered with a black mesh. They were spray painted.
The hands were cut out from foam board, wrapped with foam on the sides. I also did joint compound and primer. Then the wrists were made from cereal boxes with pencils stabbed through them, then covered with foam and painted.
The legs were a nightmare for the kids to walk in! They move VERY SLOW in them. They were made from styrofoam that was covered in poster paper and spray painted. I rigged old shoes to the legs because the legs kept twisting sideways! I hot glued Velcro straps to the legs that strapped in the back.
The hat and spiked hairdo were made from cardboard.
These were inexpensive to make (lots of hot glue and spray paint = burns, blisters, and paint fume buzzes/brain damage). They took a ton of my time and sanity, but my kids really enjoyed the outcome. They got to be the center of attention and they won a radio Disney contest vs. 300 other kids. It was all worth it!