[inc]

What are the obstacles for a hobbyist who wants to build a simple quantum computer?

[chrjozefharibo]

For solid state qubits (spin/flux) you need:

* e-beam lithography: expensive machine

* high quality materials (GaAs 2DEG, or reproducible Josephson junctions): you need collaboration with other scientists

* a huge supply of He4: money

* a dilution or He3 fridge with He3 in it: more money

* a lot of low-noise amplifiers and electronics: collaboration and a lot more money

And a lot of time and persistence.