Summary

Step 1: google Okazaki fragments. Step 2: skip ahead to a Printrbot, and build backwards to a version 2 Prusa. Uses mostly standard hardware.

Instructions

uses 3/8" smooth rod, 5/16" threaded for the z axis, 2 inch aluminum flat stock, and 3" aluminum channel for the x-carriage,and #8-32 screws 1.25 inch long. It is also designed to use cheap bronze bearings ( http://www.use-enco.com/CGI/INSRIT?PMAKA=404-2499&PMPXNO=30822520&PARTPG=INLMK32 ), and has room for a second (mirrored) extruder. Hack away, comes with parametric openSCAD files, make a 4 inch bed version, whatever floats your boat
Special hardware: uses metric m3 bolts and nuts for the motors, small gear, and pulleys. #6-32 for the z-couplers and x-carriage tensioners. 3/8" long #8 for the tapped holes on the belt clamps. 3/8" bolts to bolt the top plate to your board/workbench, don't over tighten or the aluminium top plate will bow.

Reprap Okazaki .375 version