How can I use trimmed surface with lunchbox in grasshopper?

I want to use a lunchbox using the surface shown in the picture. What should I do?

If you can, please show me an example.

if it’s all planar, you can do this
image

otherwise you’ll need to come up with an inclusivity test that works for the kinda geometry you’re working with after you split
image
the diamonds with the boundary curve of the parent surface.