Round wooden bars and conical poles can be easily made.
Inexpensive and simple construction.
If you want to make a round bar shorter than the jig, cut it later or increase the length of the bolt.

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All plywood thicknesses are 15 mm.
Bolts are M8. The bearings were fixed with two-component epoxy adhesive.
A slightly larger sized circular saw would be more suitable.

Be careful not to overload the table saw and injure yourself.