This can be printed with no supports if the magnet holes are placed facing up on the print bed. Note that this is a remix of the 0.2mm clearance original only. For materials other than PLA, this clearance may not suffice as stated by the author this is remixed from.
I glued my magnets in but the fit is fairly tight so the glue can likely be skipped. I found it easiest to stick the magnet to the jaw of a pair of channel locks and then squeeze the magnet into place. It doesn't take much force and seats the magnet very nicely.
The author remixed this model.