In regards to the geometry, I took the chassis that I constructed using weldments then within the same part created midsurfaces on the geometry. saved the part as a step file. In the step file I deleted all of the solids and saved again. Inserted the step file into a new assembly along with the wall surface and saved the assembly as a part file as opposed to an assembly opting for the option to only save surfaces and exclude bodies.


Still had to tidy up the geometry when I imported into Spaceclaim, but it did the job nonetheless.