In sci.space.tech Neil Halelamien wrote:
How difficult is it for a non-government group to build an effective
ion thruster? The only ones that I'm aware of have been built by NASA
or the ESA.

I'm particularly wondering about this in the context of JP Aerospace,
which has announced plans to construct an orbital airship, using a very
large balloon equipped with ion thrusters to reach orbit. They look
like they might have the balloon part handled, but I haven't heard
anything about what they're doing with regards to the ion thruster.

The ion thruster part of it is comparatively easy.
Making a hypersonic lifting body with a performance several hundred times
better than any in the past is the hard bit.