I saw a jr. high that had a make it and take it club that made
greeting cards on extended lunch breaks- holiday themed at least when
I visited, they were making St. Patrick's day cards. The two teachers
put together kits in ziploc bags. They made 25 kits- so 25 kids could
participate. Kits had precut paper and some trim (ribbon etc). They
had 2 samples and kids went from there- some making their card just
like the sample, some changing it.
Something along those lines might work, especially around the favored
holidays- Valentine's Day, Halloween, St. Pats.
I understand how you feel- and our school struggles with similar
problems- I think the idea is a good one. Good luck-