Not sure if this idea is fantastic or not but it sounds like something nice to do.
Sell entries to a lottery type drawing with all proceeds going to a charity in the name of TL. Perhaps Child's Play which is appropriate to the interest of the group?
Make them cheap $1 per entry, with a max of $10 per member so that way it doesn't become a competition on who can donate the most. Honestly risking $10 for the machine your building is nothing and if you lose well congratulations you gave to a good cause.
No idea if this is within the rules/guidelines of the community but it just feels like a good idea. People get a shot at a great build, they do something good, and TL gets to do something great as a whole.