Make your printer home it's z-axis a little lower so you can fit a glass plate on top of the build platform without the extruder nozzles crashing into the glass.
I've made it much shorter and snugger and there's no more wiggle. It works the same way as before except now it only fits over the part of the board directly underneath the endstop switch.
The shim is now 3.2mm high, which is somewhere between 1/8" and the actual thickness of my 1/8" glass plate.
1/8th inch is 3.175mm and this shim is only 2.5mm but there is more than enough action on the leveling screws to make up the difference.
Layer Height: 0.20mm
Extruder Temp: 230C
HBP Temp: 110C
The shim is no longer centered on the device. It now sits to YOUR left of the z-axis drive-shaft, directly under the endstop switch. The little notch faces the back of the machine and will fit around a support on the backside of the board.
Move the extruder carriage to the front the printer and lower the build plate so that you can easily reach behind the z-axis drive-shaft. Fit the notch in the back first, then roll the shim forward and press down. It's a tight fit but should click into place without too much forcing. To remove it pull up on the front and it should pop off.
If it falls between the two boards you'll need to get a flashlight and fish it out. If it falls behind the rear board it might fall all the way down if you jog the plate up and down a little. In either case it's possible to get the shim jammed against the drive-shaft and potentially harm your machine so be careful if it falls in somewhere.
Printed at .20mm, 2 shells, 30% infill. I want it to be fairly rigid so that the z-axis returns to the exact same position every time, but my settings are probably overkill.
You don't have to remove the back of your machine. Just lower your build plate until you can easily reach behind the Z-axis rod and fit this over the back board of the z carriage (behind the piece with the M logo). The notch in the shim faces the rear of printer and should be centered right behind the rod.