Thanks for your nice comments.
@calvin:The groundwork is made from a product that is called in german "Holzspachtel".
It is a sandy paste for filling holes in wood. I would translate "Holzspachtel" in wood putty.
I hope you understand what I mean, my german is much better than my english
The stowage is Hobby Fan, HF048
@Peter: I have masked the edges of the base with tape, the wood putty is not very thin, so it won't run over the edges...