At long last working on the copper frame for the low credenza. Part of the frame will be joined with standard copper fittings, other sections of pipe will be joined by round wooden pieces.

I turned the piece of cherry so that the ends fit inside the pipe, and the middle portion is the same as the outside diameter of the pipe. I then mitered it for the 90° angle. It'll be a smooth transition along the frame from copper to wood then back to copper again. Awesome.

Here's a pic:

A piece equivalent to the part with the blue tape is inside the copper pipe.  Perfect fit. You can see the piece with tape is a little bigger, so I'll need to correct that, but you get the idea.