Through the years Tico Vogt has made miter jacks. Currently he doesn't show one, but Tico is a maker, and if you asked, and met his price I imagine he would make a person one

Currently the only place I am aware of that makes them, or has a working plan is Red Rose Reproductions

I would think that like Tico, if you asked Ron Herman about one, you could work something out. I think if I bought a used one, he would be who I would look at for one.