Summary This is just a simple fridge pen holder. You'll need 4 neodymium magnets: 4mm Diameter x 2mm Thick Instructions Printed with Cura: 0.2 layer 0.8 shell thickness (0.4 nozzle) 20 mm/s bottom layer 30 mm/s outer shell 40-50 mm/s print speed Time: about 12min Find attached the skp sketchup file in case you want to modify it.