Glass build plate clip for PowerSpec 3D Pro

This is a remix of Harlique's build plate clip: this version has a channel so it fits over the nut on the build plate without removing it first, and it sticks up an extra milimeter or so.

To install it, simply slip it over the existing bolt on two opposite corners of the build plate, without removing the nut, then secure with a washer, lock washer, and M3 wing nut.

Install the first one tightly, then put the glass plate in place, and then install the second so it holds the plate securely i