Magnetic Mounting Tabs for Glass Printbed. Goodbye clips! Steel balls make single-point contact on glass for consistent positioning everytime. Customize according to your own machine using the included SCAD file. It is essential that only the steel balls should touch the bottom of the glass plate when mounted. Glue the balls and tab magnets first. Install the tabs on your machine. The balls should be higher than the two magnets (plus a small gap) stuck to each other. To make sure there is a thin gap between magnets, place a shim (2-3 sheets of paper) cut to shape to fit on top of the tab magnet. This ensures there will be a gap between the two magnets. Stick the second magnet on top of the tab magnet, sandwiching the shim. Try placing the glass on this setup. The glass should be slightly higher than the balls, barely touching them. If not, add more shims. Then glue the glass on top of the second set of magnets. When the glue dries and you remove the shims, only the balls should be touching the bottom of the glass plate.