I love my mag mounts. I've purchased a couple Scosche Magic Mounts in my day but 30$ for some silicone and a couple magnets sucks. I picked up a couple of belt mountable magnetic tool holders for 12$ a piece and it turns out they're mounted with an M5 compatible threading.
Printing instructions: Add a pause at the beginning of layer 41 and at the beginning of layer 75. On layer 41, drop an m5x8 Flat head machine screw in there, on layer 75 drop your 1/4"-20 nut into the slot and resume printing
I printed in ABS, I'm sure PETG would work as well. I avoid PLA for this as I use mine on a magic arm in my car and the heat/uv would quickly kill that.
My print settings for this were the VORON part standard.
- layer height 0.2
- infill 40%
- top and bottom shell layers 5
- wall loops 4
I use gyroid infill pattern because I like it.