This is part of my stackable, modular, mini homelab project.  This fits a Lenovo Thinkcentre.  It should print facedown without supports on an ender3 235X235 bed if you place it at a 45 degree angle on the bed.  If you have a bigger printer, it will probably look better printed flat with a few supports.  Ignore the terrible print quality in the sample pic.  I printed this on an old uncalibrated ender as a prototype before I got my A1.