The biggest obstacle for me is to make nice curves with a panel saw or a hack saw.
After sketching about 10 different lay outs, I settled for two curves.
I flattened the back of the board for the supports, and then I marked the finished size out on the board regarding the length / height of the supports. And cross cut the pieces.
Next I used a divider to make some pleasing curves and I clamped the two supports together and tried my best to saw near the line.
The convex curve was fairly easy to do, I just had to remove the waste every once in a while, and then come back at another angle.
The concave curve was a bit more difficult, but a hacksaw can follow a curve if it isn't too tight, so it ended up OK.
A rasp would be great for cleaning up such curves, but I had to resort to a couple of files and some 60 grit emery paper.
After that I marked out for where I wanted the hole for the dowel to go. I sandwiched the supports between some sacrificial scraps of wood and clamped it all to the table of the drill press.
I found a 16 mm drill and drilled the holes in one motion.
I ripped a piece of wood some 3/4" square, to make a dowel. I tried to find a piece of wood with straight grain to make it easy for me during planing.
A sticker board was set up and I started by making an octagonal. After that I simply tried to turn the dowel for every stroke, and it quickly turned reasonably round.
The sticker board was not helping anymore, so I changed tactics and held the dowel in my hand. That worked for a while, but not very well.
Finally I clamped my plane upside down in the vice and used both hands to maneuver the dowel over the blade. That trick gave me a lot of control, and the dowel ended up very round.
Finally I sanded it to an even rounder shape and checked that it could enter the holes in the supports.
Trying to saw a curve.
Rough shape of the supports.
Getting ready for drilling.
Stock for the dowel.
All pieces of wood ready for assembly.