Solid model from this?

I need some instruction which is the easiest way to make closed model from this.( or start from beginning?) It was designed fast for presentation, but I need it for FEA analysis as isotropic material. With ShrinkWrap I got 1,2GB model that crashes.Start from scratch?
mod_02_24.3dm (15.6 MB)

Surfaces, polysurfaces, open surfaces, bad surfaces, curves, dots… this is going to take hours, I’m afraid.
It is possible, but with lots of patience involved.
This is signal for troubles:

Some tidying up at the beginning would also help.
I would start from isolating and rebuilding the main components making sure they are closed.

Thanks Piotr, I was afraid so, our friend made simulation on more simple model.
It was designed for competition, mostly presentation.