This is my XY plotter that I created to test out our ARC code for our multi axis (up to 254 networked) stepper motor controller called TinyG. You can read more about TinyG here.
synthetos.com/wiki/index.php?title=Projects:TinyG

I do realize that it would not take much more to create a z axis and make this a CNC machine. This is the plan. However if anyone else wants to mess with it. Please go for it. Also, if anyone is in the Washington DC metro area and wants to mess with the machine let me know.

The metal parts are all made from the contraptor frame work. (http://www.contraptor.org) However, that being said you do not have to drill the holes in every part. Just drill them where you are going to need them.

All metal is aluminum with the exception of the Y axis "angle rails" these are made from home depot steel angle. Both steel and alum angle is 1" x 1" x 1/8". Possibly the coolest thing about this design is the fact that all the stuff that needs to be accurate is cut with the laser. Another cool feature is your size limitation of this is really only limited by the length of lead screws / angle rail length you can get. This design should be easy to support 6 - 8 ft tables with no real "changes" needed. (I think..)

The bearings used are 805 regular skate bearings. (5mm centers.. or 5/16") All hardware (with the exception of the 5/16" bolts used on the "trucks" for the bearings) are 10-24 and 1/4"

Threaded 1/4" rods are what are used to "sandwich" the parts together.

The wood is all 1/2 inch plywood. Pick your poison. This should work just fine with 1/4 stuff doubled up. I am able to cut this on my 40W epilog laser in 1 pass ever since I picked up the 4" lens.

This is a design for a /really/ inexpensive linear axis mechanism for an open source selective laser sintering 3D printer that I've been designing (but it should be generally useable for anything that requires a one or two axis system). This is a follow up to the selective laser sintering alpha one dual Z tables that I recently posted ( thingiverse.com/thing:3390 ).

The innovations in this system are its extremely minimal vitamin count -- only a handful of bolts, washers, and nuts are required. It also uses several long pieces of kapton tape as a linear slide bushing, to dramatically reduce friction and drag (though regular old scotch tape may work just as well ;) ).