LEDs are installed, wired up and working on the diffuser. The plastic I originally planned to use didn't give me enough diffusion, so I designed a hollow T profile printed with single walls and no infill. This worked well for my purpose and it had the nice side effect that it held the LEDs in place.
Still a bit of hotspots where the LEDs are, but much better than the other plastic I've tried
The main barrel is assembled and wired up.