This evening, I cut out some circles of the appropriate radius. Thsi circle cutter isn't really well suited for cutting through thick material like this, so only one of the two circles came out the right size.

I also made a rectangular block with curved ends. I'm hoping that between these, I'll be able to make some good bends.

I bought this 3/8 cove cutter for my router.

It did a good job of cutting a groove in the face of this block. The hockey puck prooved too small to route and hold on to, so I abandoned that piece.

After cutting the previously shown block in two, I glued the two pieces together so I could make a 90 degree bend around one block, then make another 90 degree bend in a different plane immediately after the first. Here they're shown gluing together.