[dexwiz]

That kind of technology is still science fiction when it comes to medicine. Any sort of nanoassembly you may read about is for more homogeneous layers of specific materials, not individual organic molecules. There is research into using designed proteins as factories, but that is nascent technology, and far more complex than spool of filament.

[popf1]

I should have said DIY chemical reactor or something similar instead of 3d printers

[dexwiz]

You can set up a home lab, in many places it is legal if you spend the money to set up a proper lab and register with local regulators.

But chemistry is very dangerous. You have to properly dispose of waste. Many precursors to drugs are poisonous, flammable, carcinogenic, or even explosive. Even trained chemists have lab accidents. Many chemists over a certain age are blind or deaf on one side.

You know who builds DIY chemical reactors? People cooking meth. It doesn't end well.