This allows quick access to the PTFE slots, and removal of the MMU or accessing a broken filament, very easily.

It uses 10 collets from Amazon..: 

https://www.amazon.com/dp/B0CQTCR65R

and four 6mm x 2mm round magnets..:

https://www.amazon.com/TRYMAG-Neodymium-Magnets-Whiteboard-Science/dp/B09QHT4W1W

I used PETG, .3mm layer height and supports only under the two side tabs.