Basically it's just a big wheel driving a small spindle, so surely that must be easy enough to make from a old bike frame...
This idea was to use the rear triangle and bottom bracket. The spinner has to turn the wheel by hand, and keep in contact with it, so half the rear triangle had to go. To get the wheel to align reasonably with the spindle pulley (or whorl as spinners seem to say) I had to crank the chainstay over considerably, which needed some hot forging. More hot forging to draw out a spindle from a bottom bracket axle. This comes to a fine point (it's what Sleeping Beauty is supposed to have scagged herself on). A 3D printed pulley finished that part off.
Now, it needs to stand on something. It needs to be at a convenient height to use standing up, so my first idea of using the headset and seat tube was out. I cut the front tubes off, and used the top tube to extend the seat tube to the right height. A flat handlebar forged into a smaller angle makes a reasonable tripod base, although not as robust as it might be. Still, it works.
And here it is...
And a detail of the spindle
