How can I turn this open surface into a solid?

note: the curves are not planar, i don’t know how to make them so…
vtora chast.3dm (705.3 KB)

Solid.3dm (794.5 KB)

For the circular curves you can either use sweep 2 with given cross section or you can do it with revolve.

thanks for the answer, but i can’t open the file, beacuse im working with rhino 5.

Solid_r5.3dm (795.0 KB)

The approach is the same either way, but to be clear what do you want A or B?

They don’t currently intersect… extend almost solves that, but there is an issue in the bottom. Still not hard to correct.