find everything (updated STL and OpenSCAD files) at:
https://github.com/makevoid/RepRap_3DM1
this is a fork, simpification, testing of a modified who's wallace, that in my opinion in an awesome simple design, that we just upgraded for our needs
the STL of the parts all on the print plate is just for show, you can use them but you will probably find the updated files (and customizable openscad files) in the github repository
there is a download zip button on github on the right!
all stl files are in the folder unsurprisingly named stl
enoy :)
there are some missing pictures of other 3DM1 printers which hopefully will be added soon
This printer design is made by Giuseppe Di Marzo and me.

Last photo is a sample recent print with 0.25 layer height - 0.35 nozzle size - very low outer shell speed, 65 inner shell speed

model is T-rex by Makerbot Academy: http://www.thingiverse.com/thing:308335

Build plate is Acrylic 0.8mm
Printer size is scalable at your choice, start from the X axis, then Y and later Z. You can easily scale the Z axis (by )
that's the awesome thing of the Wallace printer, easy scalability!
You don't need fixed axis measures as smooth rod, threaded rods and build plate (two piece of acrylic) can be the size you want
we build a 3DM1 with a 32cm x 22cm x 18cm (XYZ) print area using 8mm rods
you can easily regenerate all the STL from the OpenSCAD project using 12mm rods on the X and Y axis for even more stability or just 12mm rods for the structure (threaded rods) and 8mm rods for the movements (smooth ones)
On the Z axys you can use smaller threaded rods as well like 6mm to increase precision if you are making a small printer
Use extruder nozzle size adequate to the size of the printer you are building, for a 12x8x6
tips:
make X the longer axys
make Y shorter than X
make Z a bit shorter than Y (unless you fix the top threaded rod to something like a wall :) )