OpenForge Cut-Stone OpenLOCK Angled Floors

This is the second to last set of cut-stone [OpenLOCK](http://www.thingiverse.com/thing:1833963) floors. I've expanded on openlock by adding 2 additional floor shapes.

We add OA as a 4x4 diagonal tile to give you a larger alternative, and YA as a 2x2 angled tile to give you a smaller alternative.

For instructions on how to get started with OpenForge, we have a set of [tutorials](https://github.com/devonjones/openforge-tutorials/blob/master/README.md). Want to sell OpenForge prints? Want