Giant Lego inspired Christmas tree. Simple to print, no support needed. Can print 7, 8 or 9 layers depending on how much time you want to invest (9 does look best though). This is my first model that I've made myself so nothing complicated here. Can be printed with minimal base, walls and stepped infill - especially if you're running out of green filament with two layers still to go...
Doesn't have to be a Christmas tree, can just be a giant Lego pine tree (3471) instead.
I printed on an Anet A8 and the largest layer fits within the print bed (fairly) comfortably.
It sort of snaps together but best to glue the sections together for stability. May need some shaving/trimming where the layers join.
Overview and Background
Lesson Plan and Activity