At first I thought I might try something a bit more wavy for the cabinet sides, but I decided to go the easy route for this build and just do a simple curve.
I cut a curved form.
Then duplicated it.
Draw a line tangent to the curve at both ends. (All this is in the instructions at the Curvomatic site in both video and text).
Draw a line between 20-30 degrees from the previous line (I went with 25).
The reason for the second line is to position the straps at the best location for pulling at the angle that works best.
I now know the length I need for the 2x4s the forms mount to.
I was out of 2x4 stock, so I ripped a 2x8.
Round the ends so the straps can slide easily as needed.
I doubted the strength of 1.5" thick pine under pressure, but I wanted to try it anyway.
Forms ready for the first dry run.
Secure the bottom cheek.
The pine flexed rather a lot, but I still got a nearly perfect front edge curve.
The top cheek needed a little repositioning and the pine needs to be made stronger, because it is too thin for this much pressure.
The trailing edge needs work. I need to add another section or two on the top cheek.
This was my first dry run test (no glue) and I am pleased with what I see.
After some adjustments, I will try again tomorrow.