Ok, that was the easy part. Now you need hardware. Your local iron works will be really helpful here, unless you have a metal lathe, a welding machine, and a way to temper high carbon steel.
Here are the parts you’ll need.
1- A 3-4cm solid steel shaft, welded perpendicular to a thick steel plate (which will be anchored to the floor later)
2- A ‘receiving’ tapered sleeve. which slips into the underside of the wheel to remove any play. It has a set screw so that it doesn’t move after being set into position.
3- A pillowblock and bearing set into the underside of the flywheel, this doesn’t actually support any weight, just prevents sideways play.
4- A cone which is made with a morse taper. It goes in the bottom of the wheelhead.
5- A receiver block which has a similar female taper to receive the cone. This block is set into the center of the bottom of the wheel head.
6- A cone receiver (with morse taper), which fits into the top of the shaft. The top of the shaft is tooled with a female taper to receive the cone receiver.
The first picture shows 4 cones and 2 cone receivers. The angle of the receiver is wider than the angle of the cone so that the only part of the cone to touch the receiver is the very tip of the point.
Next picture shows the wheel with parts 4,5,6 all fitting together. This area supports the full weight of the wheel. Use a nice heavy grease for lubrication. These parts (4 and 6) have been tempered and they are made from high carbon steel. I’ve kept them lubricated, and have observed no appreciable wear in the 3 years I’ve had the wheel.
These last three pictures show parts 1,2,3. The bearing’s internal diameter are larger than the shaft, so the tapering receiver sleeve slides up into the bearing AFTER THE WHEEL HAS BEEN SEATED IN PLACE. This is very important so that the wheel is fully supported by the cone. The tapered sleeve should not be forced into the bearing, just slid up until it engages lightly, then secured with the set screw. My set screw is adjusted with 4mm hex wrench.
This was all fairly easy for the craftsman to make for me, but I ended up paying a lot for his labor. All the parts were made from scrap so materials were free. I think labor for something like this would be much less in the U.S.