I made this printer, but I broke my nerves with dual 3D printing and at the end it was reworked to single extruder printer. 400W Fortron PC ATX PSU was used. It was with 2 homemade 0,4 nozzle hotends( http://www.thingiverse.com/thing:955315 ) - 70 mm offset, bowden type extruders. Electronics - Mega2560 + RAMPs 1,4 + Full_Graphic_Smart_LCD_Controller + 6 NEMA 17 motors. Malrin Fimware. Achieved 0% backlash effect with this type of Z axis + 10 mm tr3 trapezoidal rods. Working area was: 1/ As dual extruder printer with 210x200x4mm glass- XYZ - 210/190/300 mm; 2/ As single extruder printer with 400x200x4mm glass - XYZ - 398/190/300 mm for PLA prints and 210/190/300 mm for ABS ones. Manual control for 40 mm fans for hotends/always ON by default/ and manual control for 30 mm fan ducts with potentiometer for each hotend. Sourse files (for laser cutting and references) uploaded for AutoCad 2010 or higher version. You may use this ( http://www.thingiverse.com/thing:974558 )heatbed version, it should be better. Use my (bowden version) extruder - http://www.thingiverse.com/thing:662780 with mine or fishbone gears or any 1 bowden type extruder with 50 mm offset for mounting holes. May use my LCD case - http://www.thingiverse.com/thing:743724 or any 1 for Full_Graphic_Smart_LCD_Controller and drill 2 holes with 50 mm offset in the back of the case. Clamp for e3d type hotends also uploaded - You have to rework 30 mm fanduct. Frame sides are identical so You can choose left or right for electronics, LCD, potentiometers and PSU/ spools and extruders. The printer is for 10 mm TR3 trapezoidal rods and for this - http://www.technobg.com/uploads/com_article/gallery/thumbs/256x256_a244218b8c02e17641cfef12d9409c1ebf5d9142.jpg type of round TR3 10 mm (D x L) 22 x 15 (mm) nut, that is 3 mm cut from otside diameter!!! Use the same ones or a lot of rework is needed! All parts for lasercutting can be made from 8 mm plexiglass instead of MDF, but the prices...: MDF 8 mm ~3,5-4 € for m2 ; Plexiglass 8 mm ~40-50 € for m2. Also you have to use super glue, special glue for plexiglass, xylene or chloroform (you have to pay attention for last 2) to assemble the parts. More photos here - http://www.trendi3dprojects.net/X2.html If I am missing something - post a comment. 16.09.2015 Smaller version soon... 18.09.2015 Smaller version -> http://www.thingiverse.com/thing:1022436 Basic things needed: Mega 2560 - x 1; RAMPs 1.4 x 1; A4988 or DRV8825 Stepper Motor Driver x 4/5; NEMA 17 step motors x 5/6; RepRapDiscount Full Graphic Smart Controller - x 1; Heatbed MK2a/b - x 1; Endstop mechanical limit switch - x3/6; 500 oM 6 mm axis potentiometer - x 1/2; 400 x 200 mm 3 or 4 mm glass - x 1; e3d type or homemade hotend - x 1/2; Real 400 W PC ATX PSU - x 1; 608 bearing - x 3/5 - 1 for X idler and x2/x4 for M8 rod for spool/s; 6000 bearing - x 3 - for Y - 1 infront of the stepper and 2 for back side; LM8UU bearings - x8/10; SC8UU - x 4; 12,5 x 17 mm on/off switches - x 5 - 1 for On/Off, 2 x hotends + 2 x fanducts; Same type but double switch with I - 0 - II - x 1 - for white and blue light on carriage and printer; Use Big1x2_All_AC2010.dwg for reference for M10 rods number and lenght, 8mm smooth rods number and lenght, nuts, bolt, washers. Use super glue and 2,9 x 13 mm screws for MDF parts assembly - LCD holder, PSU bed, Z step motor mounts.