I added a glass bed to my CTC Bizer. This is what I made to hold the glass in place.

This solution does not pertrude above the buildplate and does not hinder the extruder.

It uses the four screws that holds the aluminium plate to keep the plastic locks in place. There is an oval hole to be able to adjust the lockation of the lock in relation to the aluminium plate.

The holes that allow the screws to contact the glass plate are 3.75 mm from the ledge. So the aluminium can't be thicker than that, otherwise the adjusting screws will not work.

Hardware:
8 M3 screws (I jused 8mm long)
8 M3 nuts