Update 03/15: If you happen to use this as a Z axis stop and want to do sensorless homing (it is not recommended) on an Ender or similar style printer, the stallGuard threshold must be set low enough so that the Z motor doesn't torque the screw so much it bends the bracket down and bends the rod. I am testing another type of stop that slides over the threaded rod and stops the carriage at the nut, but it is not quite ready for primetime.
For those of you brave souls employing sensorless homing, if your printer happens to use V Slot rollers to move around, this will give them something to run up against that won't damage anything or make a lot of racket.
If you aren't using sensorless homing but want to keep your carriages from going places you don't want them to go then this works for that as well.
Rather than plowing the nozzle into my bed, this allows the wheel to seat in and the more force that is applied by the wheel, the more holding power is applied by the end stop. Just like a wheel chock for a car... except for your printer. At least.. that is the theory.
You will need 1 M4 x 10mm socket head screw and some form of nut to fit the extrusion. There are printable ones to be found.
This is the first release of this thing, but it is not a filament heavy part so if it doesn't work for you drop me a line and I can adjust it.
Filament Geeks Maker Series PETG
Print with supports touching build plate. I used a zigzag support with a ceiling and support raft. They snapped right off leaving a clean bottom.