This fridge magnet pen holder is basd on riskable's low poly vase.
Print in SPIRAL VASE MODE with zero top layers and at least 3 bottom layers.
These are really easy to make. Simply download your favourite spiral print vase and use the plane cut feature in mesh mixer to give it a flt side. I slightly angled this so it leans outward slightly.
Purchase some adhesive magnetic sheet, cut to size and stick on the back.