Merzo, Luke, indeed that's the method I have planned for tomorrow. It will be a bit of a hassle to get the drywall stuff right inside the rings. I think I'll first make the green inner part (also from thinner card and smaller than the outer layer, of course - this also has to be tested first - and then the white outer layer to glue over it. The "cut-after-drying-as-a-cylinder" was also my thought on how to tackle this problem.
Thanks for thinking along with me, this gives me the idea I may be on the right track...
And Merzo, your explanation was spot on. only "the ears" puzzle me a bit.
