Rather randomly, I picked up some bisque hearts with magnets already glued to the back at the local primary school fair. I'm sure you could do something similar with air harding clay or that coloured stuff you stick in the oven to harden..Fimo?
Lala enjoyed painting them with Acrylics. Once dry we coated them with PVA and pretty tissue paper, and more PVA. I finished off by running a black calligraphy pen around the edge.
Ta-da - some pretty Valentine's magnets. How was you're weekend?