This is a 3-wheeled option for the Z-Guide that rides on the 20mm sides of the vertical rails instead of the inside slot of the 40mm sides.This also has easily adjusted tension on the 3rd, outside wheel.

It's designed to work with all of the standard parts required for the standard D-Bot Z-Guide. It should print without supports, just put the 3rd wheel facing upwards on the bed.

I haven't printed this yet, but will try them after the Holidays when I get some more free time.