Update 4/11/2023: Tweaked the tabs that go into the extrusion, and pulled the mount out 2mm further to give better clearance for your things. It's a snug fit, but fits well.
I liked Citruspers Gridfinity mount, but I wasn't fond of having everything mounted so high.
This variation has the tabs higher, so it can be mounted at bed level and keep all your tools lower to the desk.
You will need either an extrusion nut insert, or a hammer nut, and a screw that fits.
Support is needed for the tabs, but the inside has been hollowed out to reduce material usage.
The author remixed this model.