I re-created these based on Steamerzone's parts. I wanted to be able to quickly remove things and not have to cut a zip tie every time or strain the wires even more by twisting things to the side to get under the glass. This allows you to just pop the O-Ring or Rubber band off. Of course you can still use zip ties as well. I also rounded things off more for smoother edges. The top grooves are also a little deeper to allow better grab on the wire loom by the O-ring.
I used M3x10 bolts. Shorter would work fine, these protrude just a tiny bit on the bottom. I believe the O-ring is about 13mm ID, but anything close should work.