Hi Lars,

>>I've only just started to imagine those intersections on a 3d-surface, and thought I would start easy with a cylinder or something...

With the current MoI toolset you will struggle and have to make a lot of construction for the interweaving surfaces around a cylinder (or sphere etc).
For solid work I now usually use VC pro which gives more advanced filleting/shelling etc. The 2 interweaving surfaces I made (image posted earlier in the thread) I imported them into VC pro and bent them around a circle.