One idea I tried after the previous post, was slicing the tube into 16 rings. The idea was to glue the bricks to the tube, with the bricks stacked vertically, then offset the rings after the bricks were attached. That approach failed. I was unable to cut the rings smoothly, resulting in large gaps between them. When stacked, they looked horrible.
In the end, a simple change of adhesive and application made the difference. First, I abandoned both hot glue and epoxy. I discovered gel super glue has sufficient open time to position the bricks, but also sets quickly enough that clamping and supporting the bricks was unnecessary. I addition, I realized the important joint is between the bricks. If the bricks are firmly cemented to each other, the connection to the tube can be a series of comparatively weak joins. Less glue on the end-face means less glue to smear, and less chance of accidentally gluing the template in place.
Many people have asked how I cut the LEGO bricks. Initially, I used a sharp chisel. That was tedious, as each brick had to be clamped. After that, I switched to a rotary-tool held in a fixture, with a standard abrasive cut-off disk. That worked well enough. Finally, I hit on chucking a Dremel-sized circular saw blade into a drill press. That provided a rock-solid platform. Better still, once the height was set it didn’t vary. Unlike the abrasive disk, the bricks weren’t heated by the saw blade. No molten plastic flying around. Using this method, the bricks required little-or-no touch-up work with a sharp knife.