This is what I did last year. It's both STD and O. The whole thing was made out of xps foam. After Christmas, I stored it up in the garage rafters so I'll be trying to reuse it this year. The central tree platform is made out of wood. If you have the ceiling height, then a tree platform is an easy way to squeeze in another loop.
I'll change it up this year but I'm not sure how yet. I realize it's a little over-the-top but maybe you can get some ideas from it.
