As one of the resident amateur xenobiologists, I can tell you that contests for ‘newly designed’ only characters with physiological traits randomly picked by the contest judge could possibly keep the topics fresh and vary the challenge level. I’d be happy to cast a secondary vote based on anatomical logistics to assist in determining tiebreakers in any contest I don’t enter or don’t make finals for.
Example: XC#1, human-sized, meat-muscled, three legs, dancing–twirling should come easy if the legs are roughly equal, All the big toes on the same side of the three feet can make sense if there is only one big toe and not in the center.
For that matter, you might hold a contest for people to make in hm3 entire pictures of single items they’d like to see in the future. That would bring an element of pride–“I made the inspiration for that out of TWO HUNDRED LAYERS so you can have it in one!”
Another idea would be to reuse some of the more challenging pop quiz ideas and encourage using the week. I’m guessing Jeff wouldn’t mind?