UPDATE: After some use I realized the arm being on the right side makes levelling the build plate a royal pain, so I changed it to the left side. I'll leave the right side up in case you still prefer it. I also tightened the inside of the socket by 1%, hopefully just enough to make it snug (I was using a piece of paper towel to great effect).

UPDATE 2: Added a blank version by request. It's for the left side so just mirror it in your slicer if you want.

I liked the functionality original but only wanted the hangar on one side, so I removed the left arm. I also replaced their logo with the Elegoo "e" on the front of the build plate as I think it fits better with the machine's design.

I printed it on my Ender 3, flipped upside-down with supports and it works fine, although on my original Mars the screw is quite inset and not as secure as it's probably meant to be. I'm not too worried though as the knob is large enough to prevent the plate from falling through the socket.

I recommend using a high infill on at least the arm and screw holder as they are the most load-bearing sections. In Cura you can do this using Support Blockers and Per Model Settings > Modify settings for overlaps.