Openscad opto endstop model

This thing is a simple openscad model of the ubiquitous optical end stop module.

Hopefully this will be useful to someone.

Note: there is an electronics design problem with this type of Opto Endstop sold on eBay. The reason is explained here
http://forums.robo3dprinter.com/index.php?threads/improved-opto-endstop-needs-some-improvement.3035/