It seems like there are a range of products that could make economic sense to manufacture in low Earth orbit, taking advantage of zero gravity and perfect vacuum.
Products might be manufactured either for:
Use in space:
Satellite and spacecraft components and spare parts
NASA Funds Demo of 3D-Printed Parts Made, Assembled in Orbit
Large structures that are cheaper to make in space than transport from Earth, e.g. telescope panels that would otherwise require a complex folding geometry for launch
Return to Earth — extremely high-value products requiring zero-g or vacuum:
Materials: fibre optic strands, semiconductor afers
Biomedical: printed organs, implants
Space Tango - LEO Commercialization Of Biomedical Applications
Pharmaceuticals
General references:
4 Products That Make Sense to Manufacture in Orbit - IEEE
Axiom Space - On-Orbit Manufacturing
This is economically enabled by much cheaper launch. In Case for Space, Zubrin estimates that LEO launch cost will get down to $200/kg, making products sold at $2000/kg viable after accounting for various overheads.
Only LEO manufacturing seems to make sense for now. Later, but much more speculatively: