Sometimes you can't just simply superglue a magnet onto a surface (e.g. your beloved old sewing machine). But double sided tape or foam would be fine. This bracket increases the magnets surface area so that the adhesive has more holding power.

For magnets 10 x 10mm, 10 x 5mm and 8 x 3mm.

I recommend using the “variable layer height” feature in prusa slicer for a nicer round finish.