Insert 4x M5x8mm button head screw into the bottom plate and thread on 4x M5 T-nuts enough so the threads will grab.

Insert 1x M3x30mm socket head screw into the bottom plate.

Take 1x M3x20mm screw. Slide 2 F623zz bearings with a M3 washer in the middle.

Push the bearings together and insert the washer bearing sandwich into the bearing tool and remove the M3 screw

Insert the bearing sandwich with the bearing tool over the M3x30mm socket head screw