I created these to hold my polycarbonate build plate on top of my Robo3d R1+ glass plate without limiting the axis on lower Z (because of clips + dual fans).
This is designed to go under the glass bed over the bump of the side magnets.
2 pieces of the same type (2 left / 2 right) should be enough, but I included both left and right in case you want better grip (only the right one was tested so far).
Edit: In the pictures you can see a gap between the bed and the holders, that is because my plates are a bit bigger than the bed and the holders bend to add more space
Update: I tried printing all 4, but noticed that there is something interfering with the top-right one (left model type).
Also I can confirm it works with regular PLA and prints well with 2/3 corners
I used eSun white FLX PLA (its semi-flexible).
Let me know if it works with regular PLA/ABS as well.