I have two ways to go here but since the gentlemen and ladies that surf the surfacing topic seem to be more advanced users, I posted my question here.

Ultimately, I want to create a simplified "dumb solid" that i can print to create a miniturized version for a key chain.

I have an assembly that was originally imported from ProE (I still have the ProE files as well). This was originall modelled in ProE as all surfaces (interior and exterior sides, with air between the walls). The main body of the assembly is a two-part assembly. Each part is made of several "Surface-Imported" surfaces. I cannot knit these to "form a solid". I exported the parts as a parasolid.x_t and then reopened it, trying to heal it. Many of the small fillets have gaps (41 gaps), and one face is "self intersecting".

The other part is the same story.

Ultimately, all I need is an .stl file that I can print on an FDM print.

DO I need to fix all the gaps first or is there some better way to do it?