I designed a larger dual head 3D printer using Generation 4 electronics from MBI, I call it affectionately TOM-BOY. It took me some time but I could not sleep unitl I designed a printer that was larger, accurate and reliable. At least I think it will be? I designed it using standard DFM policies using common parts through out. The design uses all dual NEMA11 Non-Captive screw drives on each axis. The screw I selected will give .001mm acuracy and 400mm in travel. The print area is right at 270mm+ in all directions and a bit more in the z direction.
The Hot End is also customed designed with new dual gear drive, and is set up for 1.75mm material.

Other Features:
Inverted electronics bay so you can get to all electronics
Plastic scerw locks so acrlyc will not crack
Fully inclosed with door access
Feeders for filiment spools
HBP is atached by magnets for easy access,service and leveling
All parts used to construct each axis can be printed on a TOM
*Gen4 Interface board and display bult into design

I just finished and am looking to get some acrylic not lexan lazer cut. I am hooping the comunity can help with a cheap place to do this.

I only down loaded one of the hot end parts at this time. I will down load all the parts shortly for those who my be interested. I would like to down load the final versions as I build the actuall unit.