PHASE CONVERTOR
I built my own roto-phase years ago. Very simple. First one was a 5 hp. It ran two lathes and a mill. I sold one old lathe and the roto-phase. So I built a 10 hp. I then got some more machines (and larger) so I sold the 10 hp and built a 20 hp. It ran my entire machine shop. 3 mills, 3 lathes.
Just need a bank of capacitors on the manufactured leg. That takes a little playing around with different size micro-farat to end up with a close to balanced voltage across the legs. The more motors running at one time makes it more efficient and balanced voltage. I would always start the larger motor first then start up any smaller ones. Worked awesome until I got some CNC equipment then the power just wasn't clean enough for that so finally brought 3 phase in the shop. However they are the best thing for running electric motors.............the more the better.