I got the LED strips soldered and inserted into the cylinder. I printed retainer strips to keep the LEDs in their slots. It’s now wired up to the Adafruit Feather Huzzah32 and now running a rainbow trial.
I taped two sheets of paper to make the diffuser. Not perfect but pretty effective as a diffuser.
I just need to wire up the buttons (awaiting delivery of the wires and connectors to connect to the two-pin headers include the breadboard to simplify disassembly/reassembly).