I finally finished this and it was a huge FAIL. Shapeways couldn't print it in ABS or PLA, so I printed it in their sintered nylon (strong and flexible) and made it black. When I got the parts, there was
no way of fitting the aluminum heatsink into the slots. It took me about 15 minutes to get it to move an inch. What happened is that some (a lot, actually) of the nylon powder was still firmly stuck in the slots for the aluminum bar. I tried scraping it out, but the angles made it impossible.
Screw it. I cut the arches (which took a while) scraped out the excess nylon power (it appears that the black is just a paint) and squeezed the sides around the aluminum bar... forming it as I went along.
Here's the result. It sucks:
(yes, my desk is a mess - I have several projects going on - a Raspberry Pi running OctoPi for a Monoprice 3D printer I bought; a WiFi to RS-232 telescope controller that I just finished, assorted test boards and parts bags)
This is a sample of the cuts:
Most of the space between the sides is lost material, the rest is nylon powder I didn't remove.
At least it does provide bright, even white light:
Still annoying, though.
I have several meters of LEDs left over, including 5 meters on even brighter ones. I think the arch idea is good, but 3 or 4 large
sheets of bright LEDs should be even better.