Oh, Ab, sorry to irritated you.

I decided to try my table saw KS230 on this job - and it does work. Yes there is dust - that's the very big difference.
So I do get all the straight slots faster and easier, so I can bring more effort into the curves. My good old disk sander will also come very handy, hopefully.

For power tools it is out of intrest if the cardboard is 1, 1.5 or 2mms thick...
I just have to harden it on the backside to avoid a tearing out to the material while cutting. The wooden Idea of glueing a tapestripe to the back didn't help - so I will given super glue a try.
Edit: Turning the steering wheel
And it doesnt work as thought, Ab, you are so right!
.
P S.:
I tryed the scalpel N°11 on 1,5mm cardboard and needed
26 minutes for the N°"B" to be cut out;
after this there came bulkhead "C" with an invested time of 19 minutes, so the cutting is becoming much faster after 2-1/2h for the first bulkhead - now we can talk about "progress"
Too tired to continue this night but very happy about the third bulkhead been cut.