Hi Felix,
MoI and BobCad will be a good solution for you.... For CNC stuff, it's best to stay in the NURBS world. Although STL can be sent to you CAm package and machined, it will be linear at some type of resolution.

I'll give you some examples of how to get the detail added using your BobArt with 2d geometry... All those pictures you show can be done with MoI and BobArt...

I'll need a bit of time to produce some curves to use, then make an example to present to you here..

Burr