Easy open z & y axis end caps / rod covers

These are yet another implementation of easy open / quick access end cap covers for the Thing-o-Matic y and z-axis linear rods. This implementation uses a cover which rides in a sliding dovetail joint.

For other implementations, see http://www.thingiverse.com/thing:12279 (cover is sandwiched between the wood and a plate) and http://www.thingiverse.com/thing:16415 (cover slips onto the screws which need to be loosened a little to again remove the cover).