The most troublesome issue is the hole's size being difficult to standardize, which might not match the axle very well.
Even so, it's much easier compared to working with wood or stone.
As for how to design the spool for wrapping the thread?
He doesn't need it to wrap the thread well; even loosely is fine.
Make a cross-shaped frame and fix it onto the axle of the spinning wheel.
Increase the thickness of the frame, and it can be used for wrapping thread.
His method is to make two frames of the same size, both placed vertically on the ground and connected at their eight corners by horizontal wooden pieces, forming a frame with thickness.
Fix this frame on the axle of the spinning wheel so it can rotate along with the axle.
This spinning wheel will be very simplistic and ugly. But it can serve the purpose of a spinning wheel.
The biggest potential problem during use is that the axle and the outer hole size don't match, causing it to wobble when turning.
