OpenForge 2.0 Plain OpenLOCK Magnetic Base

OpenForge bases now support the [OpenLOCK system](http://www.thingiverse.com/thing:1833963). You can now use any OpenForge 2.0 internal 1x1, 2x1, 2x2, 2x4 and 4x4 tiles with the OpenLOCK system. We've been in discussions with [Printable Scenery](http://www.printablescenery.com/) and we heartily support this open standard for locking tiles.

This set is made up of plain bases that can be underneath any tile. These also have holes for the magnetic system if you want to do both. For bases with a side that is 1x, we have to choose between openlock and magnets. The files listed as "magnetic_priority" choose magnets, the others choose openlock.

It's worth noting that OpenForge is done on a 50 mm basis, and OpenLOCK on an inch basis. The difference on a 2x2 tile is only 0.8 mm. These bases are on the inch basis, but standard openforge tiles work just fine on them. The size difference is about the same as you can get from standard printing errors, so it's entirely unnoticeable if y