An Ikea Skadis Mount for Liquid Squeeze Bottles. The ones shown are 500mL from Amazon (below). Must be printed in the orientation it hangs on the Ikea Skadis Board with supports.
Amazon.com: Yuelong Plastic Squeeze Bottle,2Pcs Safety Wash Bottle 500ml Convenient Green Soap Supply Tattoo Squeeze Bottle with Scale Labels Watering Tools for Medical Label Tattoo Supplies(500ml,16oz,1 Bottle) : Industrial & Scientific