For my Tertial iPad holder hack, I cannibalized a Tertial, but had the lamp as a left-over. So I decided to create a hanging lamp with it. I wanted two lamps so I bought another Tertial.
1 terminal block
Step 1: Cutting the frame
After disassembling the Tertial (how to: see my other Tertial hack):
* Cut two arm parts to the preferred length
* On 1 arm part: cut a hole for the plastic end cap, such that is angled 90 degrees to the other plastic end cap (opposed to being on the same side as they are by default).
* On the other part: cut the hole at a 270 degrees angle, such that when both lamps hang down from the arm parts, the wires exit the arms at the same side in the middle.
* Drill a hole in each arm to mount the arm to the ceiling
Step 2: Assembling the frame
* Reuse what parts you like from the Tertial to connect both arm parts. I used the spring holders for simple decoration.
* Drill 2 holes in the ceiling matching the drilled hole in each arm part.
* Screw the frame to the ceiling. Leave a few millimeter of room between ceiling and arm for the end cap to slide on. Note that you should screw the frame to the ceiling before feeding the wire or putting the end cap on.
Step 3: Wire up
* Feed 2 wires through the arm parts and end caps
* Attach the Tertial lamp heads
* Put the end caps in place
* Connect the wires in the terminal block
* Align the Tertial lamp heads, so they are at the same height
* Clamp the wires in the end caps
* Fix the terminal block
See more of the Tertial hanging lamp on instructables.