I will call these Corner Clips...
Now improved so the thumb screws will not dig into the bottom of the heatbed. I added small disks to interface between the screws and the heatbed. They are attached with their own little supports integrated into the design.
This thing is my idea for glass clips for use with the mirrors from Home Depot. The mirrors I purchased were 3.8mm thick. I use three of them and place them in the corners that do not have the heat bed wires. The Corner Clips have been updated to fit correctly and the screw holes are the correct size. They have been further updated to hold the glass down to the bed to prevent warping. These really work a treat and I feel are so much better than the spring clips that came with the machine. For strength I print these flat on the diagonal surface without supports. because I thickened up the design a bit, I no longer use a brim when printing them. I do use purple glue stick on the mirror though. I printed these in ABS and scaled them up 4%. It might be possible to print these in PETG but I have not had the opportunity to try, they work so amazingly well in ABS.
To use these you will want to purchase the 12x12x.1 inch mirrors from Home Depot. While you are there go to the hardware section and find the half inch long 10-24 thumb screws they sell there and buy two packs. I originally designed Corner Clips to use 10-24 set screw 5/16in long, however these clips need to be adjusted when the bed is warm and needing a tool to make those adjustments was completely impractical. Using the thumb screws makes Corner Clips a pleasure to use.
Notice: It has been brought to my attention that Home Depot in other markets sell mirrors in thicknesses other than the one i use and designed my Corner Clips for. If you have a mirror in another thickness other than 3.8mm and want this design to work I will be happy to make the adjustment.