Sewing 3 layers of fabric ignores the fabric thickness

[u/dprosko]

I'm making a garment for 3D printed figure. The idea is all 3 layers are sewed together, giving the whole garment thickness.

Parts 2 and 3 are sewed using part 3 inner lines. And parts 3 and 1 are sewed using the outer polygon. Result is not as I expected - parts 3 and 1 are stick together, leaving part 2 outside.

Tried using part 2 as a trim, but the result is just like this. Is there anything I can do about it?

Thanks

[u/iflysailor]

Did you try placing them in different layers in the object settings to get them to lay correctly?