Closeup of the end of the drum

The drum material is four strips of Douglas fir. Not optimal, as the hard and soft grain lines and the varying direction made it hard to sand the drum to be perfectly round. It's within 0.2mm of round now, which is enough.

To glue them up to the 1" square axle, I first epoxied them in pairs into two L shaped sections, after using thin screws to position the parts while it was clamped up. When the two "L"s had been glued, I epoxied all six facing surfaces - four to the axle and two between the L sections, and clamped the whole shebang. When it was cured, I fitted it to the frame with a temporary chisel-rest on the back side, and turned the square drum round.

After fitting the baseplate, I could feed sandpaper under the drum from the rear side, being careful that when I let the drum drag the paper through, my fingers didn't follow! This phase was a little scary, and it took a lot of stopping to measure with the vernier caliper until I was confident I had the diameter consistent along the whole 750mm length, within under 0.2mm.

A final surface sanding and sealing with a light coat of Danish oil and the drum was silky-smooth and ready for use.