Here, i made a mockup of what you might need to build something like this. what's missing from the drawing are the correct sized nuts, washers, bolts, and a cartridge bearing freehub with the paws removed. You could use an 11 speed hub, put on a very large cog first, which gets chained to the actual cog on the wheel, then add on top of it a 9 or 8 speed cassette, which gets chained to the crank and derailleurs. The wrench flats on the axle prevents the axle and hanger from rotating, and the solid round part of the axle is for the cartridge bearings. A threaded hole at the end of the axle is used for the bolt that attaches the hanger.
The axle could probably be made from a standard Shimano axle, and if you have a router machine, cut the flats. Then drill a hole and tap it on one end. Otherwise, you'd have to get a shop to fabricate it for you. Misumi makes these kinds of things for bearing spindles for around $40-50, but I don't know if they thread the ends so deep. Protolabs could probably do it in 3 days on their automatic machines but minium cost is $100.
The hanger could be laser cut from a plate for whatever the minimum charge is for automatic laser cutting service.
The angle plate and rod would have to be fabricated yourself. You could simply cut 2 plates and weld them at an angle. Drill a hole through the center, stick in a rod and weld it. Or lasercut the 2 plates with holes already cut out, and bolt them together with a readily available 45 degree angle joint plate, then the rod could be connected with some kind of collar. The "dropout" plates could also be laser cut, and then you simply weld it to the angle plate. Or the dropout plates could be laser cut as a flat sheet metal, and then you bend the plate into a U shape and bolt it onto the angle plate.
(Edit: oh I didn't draw the B-limit screw tab on the hanger)
