Bed holder for Anycubic Kossel

Even better bed leveling mount: https://www.thingiverse.com/thing:3158524
Except it will require few M3 bolts and M3 hex nuts.

Everything is good with these Anycubic Kossel printers, except when you print big and fast.
Because sometimes bed just wants to rotate, leading to radial layer shift and failed print.

I don't know why our Chinese friends haven't done anything to address this issue, but bed plate manufacturer prudently drilled three holes in that plate. So let's use those to stop