The first thing I do before cutting any wood is to find a shape that I find appealing. Then I make a full sized drawing on graph paper. I use this to do all the calculations for the each ring. You can purchase software to do this but I prefer the manual method; plus it doesn’t cost any $.
I use the “wedgie” sled by Jerry Bennett. You can find his videos on YouTube which explains how to make the sled and how to cut various types of segments.
Certain rings with the triangular pieces require additional clamping to prevent the triangles from sliding up when tightening the hose clamp.
When the rings are dry it is important to sand them flat. I normally use my drum sander or disc sander depending on the ring size. But you don’t need a machine to sand the rings. A simple flat piece (from on old desk) of particle board covered in laminate works just fine. I used adhesive backed sand paper. Then all you have to do is sand one side at a time. If you did a good job milling the wood and glueing the rings flat there shouldn’t be too much to sand.