Catarina Mota and Nick Vermeer experimented with magnetic ink:

I used to buy magnetic paint, but I wasn’t very happy with its strength, consistency and color, so Nick Vermeer and I decided to make our own. More often than not, things turn out to be more complicated than they appear, but in this case it was the other way around!

Nick sourced fine magnetite powder and we then experimented with several media. The one that seemed to offer the best combination of strength, appearance and consistency was the glossy acrylic medium.