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: