This is a 3 part system, The mount, nozzle tray (2 part print), and the bed bin. The nozzle tray and magnet plate can be printed separately and glued together with the magnet side facing the bottom of the tray or they can stacked and combined in the slicer pausing at the last layer before the magnet holes get covered for placing the magnets if you know how.
This uses 14 10mm x 2mm neodymium magnets plus the T-nuts and screws to hold the mount to the printer. I used m5 hardware. Nozzle spots for 20 0.4 and 5 each of 0.2-0.6-0.8-1.0. The dump bin sits along the bed so you can scrape debris of the bed into it and pop it off to dump it when needed. 6 magnets and a hoop holds it in place as well as keeping the nozzle tray from getting easily nocked off.

Printed at .2 layer height, 2 walls (.45), 10% adaptive infill, and only the mount needs supports. I printed it in pla but any reliable filament will do.