Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4905328.

This is a simple design mostly for glass whiteboards that utilizes suction cups to keep it in place.

Print with the back side facing down at a 45° angle.

There is a magnetic version that contains captive magnets to be able to use on a traditional magnetic whiteboard.

Suction Cups (1.77 Inches / ~45 mm)

Magnets (10mm X 3mm)

Note: I highly recommend rare earth magnets as they will be strong enough to hold the shelf up.

Pro Tip: Add custom gcode at Layer 20 to automatically pause the print to insert the magnets. GCODE: M25