This was inspired by user schlotzz Fridge Magnet On/Off Switch. I designed mine in Tinkercad and made slots to insert a HarborFreight magnet. This didn't require any glue as the magnet fits tight in the slot.
It works well to hold things to the fridge.The Magnet used is here: http://bit.ly/1ID1nNo
I printed it on my MP Select Mini but its so small it can fit on any 3D printer.No supports required.