I very much liked the design of this lamp - http://www.thingiverse.com/thing:92382 - but I wanted to use 2020 extrusion and to also design my own head to take cheap COB LED strips from ebay.
Mine were described as "12V LED STRIP DRL DAYTIME RUNNING LIGHTS FOG COB CAR LAMP WHITE DAY DRIVING" - www.ebay.co.uk/itm/6x-12V-LED-STRIP-DRL-DAYTIME-RUNNING-LIGHTS-FOG-COB-CAR-LAMP-WHITE-DAY-DRIVING-/172359171337.
I reimplemented the base of the lamp in openscad, designed my own head for it, plus caps for each end of the tube, one with hinge pivot. The COBs are popped from their bezels, glued into the head, and then wire fed through and soldered to the board. I then connected the two LEDs at the far end. Note that my LED strip required a couple of contacts bridging before the +ve terminal worked, which took me a while to realise hence all the solder on it where I was trying to get it to make contact!
It's very stable even with a 500mm length of extrusion but would be even better at 400mm. Note connector is for if using a few shorter sections of profile and it's untested.
If printing again, I might remove the rotate from the wire hole in the head as I don't think it's required. The mounting tabs for the hinge could also be a bit shorter, particularly on the mount, as there is plenty of wire clearance. If anyone plays around, please let me know how you get on and maybe share as a remix.
Update: OK, my profile may be too slim for the LEDs I'm using as it's slightly curving upwards after a few weeks of fairly heavy use. The head may need to be thicker or perhaps printed in PETG or ABS.
Supports are only needed for the Lamp Mount. I used Cura's zigzag with an interface layer and they popped out very cleanly.
The head is secured to the mount with an M3 bolt (aka machine screw) and a nut but doesn't have to be tight. I soldered the link cables to the LEDs, then glued them down, and then fed the supply cable just enough to solderer it down.