surface to solid fails (cannot modify surface)

Hi everyone,

I know this question has been asked frequently, but i could not find a correct way to apply this to my situation.

I am trying to convert a surface-import to a solid part in solidworks.

I have tried to knit and thicken the object, I also tried to save it as a .step and open it again but it won't work.

It's a pretty complicated part (from an industrial robot) i downloaded from the vendor, so i can't change the drawings.

Is there another way to get it solid what i haven't tried yet?

Thanks in advance,

Yannik

SolidworksSurfacing