Wedge to adjust the height of the print bed center in case it is concave. This one can be reached easily and doesn't require you to get the tools out every time. At 33 grams when fully assembled, the setup is relatively lightweight and not a strain on your y-axis. The part "Bridge" is optional, the adjuster also works without it. Use if "Cage" seems to be too loose with your build plate.
Additionally you need:
1 M4x140 Motorcycle spoke like this one - https://bit.ly/2PafmQ5 (I got mine on ebay for 3 bucks)
1 M4 nut
Felt pads like these - https://bit.ly/2KI67WJ
1 spring from a pen
If you print and install this, please post a make. I love seeing the results :)
You could probably go down with the infill percentage and make the whole thing weigh even less. I don't think that would be a problem at all, it seems very stable.