Heat bed corner bracket

It is a bracket to prevent the model table from shifting from Heatbed. Since heat resistance is required, it is recommended to output with ABS.
Corresponding Heatbed is 220 x 220 size as below.

[Heat bed 220x220](https://www.banggood.com/Anet-220x220x3mm-120W-12V-MK3-Upgraded-Aluminum-Board-PCB-Heating-Bed-With-Wire-For-3D-Printer-p-1201841.html?rmmds=myorder&cur_warehouse=USA)

Please note that Heatbed of other size has different hole positions.