3Up Bed Levelling Thumbscrew Upgrade

I was annoyed by the difficulty of getting a perfectly level bed on my 3Up when using the stock bed holders, so I've designed this upgrade. This now allows me to place the hotend directly above the bed holders, and adjust the bed to perfect level from below.
This is a vast improvement from the old method of having to move the hotend out of the way to adjust the level, and back over the holder again to measure.
I'm using an MKIII ALU heated bed, so I have designed this for M3 hardware, but