Although this is a remix of a remix, I used a 12x4.15mm magnet, I made the hole deeper to accommodate what I had laying around. 1cm air gap is enough for the printer to dissipate heat.
I used PLA+ as the main structure and PETG for the support at 0 Gap, 0 Interface Layer Top/Bottom, 0.2 Layer height and 10% infill.
The author remixed this model.