I concur that if you can get sectional curves, that's the easiest way to go. If you want an odd diameter, make a jig and go for it. I find it very useful when I'm "here" and need to get "there". For random pieces, I just bend it on my gut. For a sweeping curve, two screws to anchor it on one end. Then work your way down the length and add screws to hold it as needed.
Doesn't look like this part has been mentioned. AFTER you bend it, you'll want to cut the ends square again.