Experimental Thing-o-Matic Inspired Cupcake Z-stage

If you're like me, you were smitten with envy when the Thing-o-matic was announced; if you're even more like me, you can't really afford it (yet). I designed this as a way to retrofit some of the new functionality into the cupcake - specifically the faster, lead-screw based Z-movement and Z-shafting to improve print quality. With any luck, this mod and the 4th generation electronics will bring the cupcake into the same class of build quality as the Thing-o-matic, if in a reduced build size/poor cousin kind of way. And I really mean reduced build size - this Z-stage cuts about 45mm off the available height, so be warned.

NOTES:

1. I specified a 1/4"-16 acme screw, 152.5mm in length. The length will depend on exactly how you mount the screw and coupler on your motor. I think the Thing-o-matic uses 1/4"-20 precision acme screw, but I wasn't able to find a cheap hex nut for that, and all the flanged nuts I found were pricey and needed machining for a bolt pattern. Consequently, I went for the 1/4"-16, but once Makerbot releases the documentation maybe it can be switched. It would be best to use whatever they're using. The length will also be shorter if you're using either a HBP or conveyor.
2. For this to work your extruder has to be mounted 180 degrees from the stock configuration - in other words, with the motor in front.

EDITED TO ADD:
Version 2 of this thing is here: http://www.thingiverse.com/thing:4259

I've also uploaded modified top and middle profiles with dedicated .25" holes for the Z-rods, for those hardcore cupcakers who want a fully lasercut setup.

I've also uploaded a printable Z-motor spacer block and shaft coupler.