A simple Square Reader holder that slightly raises and tilts the reader towards the front, with a slot on the rear side for a cable and a holder on top that can hold a business card or a 1 mm thick printed sign (as shown in the cover image).

This model doesn't require any particular material or printing settings, as long as it can manage the bridge over the cable port in the back. The demo sign shown in the cover image is included as a second plate with the print file, but you can use any Make My Sign-generated sign that's 1 mm thick.