Create a flat surface from sketch frames placed on 3D sketch planes

3D Design Volume Model
1

Hello
I'm on solidWorks, I want to develop a multi-ply accordion bellows.
To do this, I created two 2D sketch blocks corresponding to the internal and external folds of my future accordion bellows.

Flat surface creation works perfectly when these blocks are incorporated into a 2D sketch

But as soon as I use them on the different accordion planes of my 3D sketch, the flat surface function is grayed out and I can't even select my sketches placed on these flat surfaces that represent my accordion slices.

Can you help me???
Thank you in advance

2

Hello

It's not very complicated. Just create a sketch with the small square and then make an extrusion indicating the distance and you can also give an angle if you have it or create a second plane with a second sketch and use the smoothing function 'insert-boss/base-smooth'. Once you have obtained the shape, you use the shell function to empty the piece, and then you can use the repeat function to finish your bellows.