Check out this 3D printer (translated) which [Arkadiusz Śpiewak] has been working on. When sending in the tip about his project he made the important distinction that it isn’t finished, but he has reached that critical threshold where he has printed items with it.
He decided to go with a design that is sometimes referred to as an H-bot. If you’re completely unfamiliar with it, you may find this H-bot design article helpful. The gist of it is that this technique makes it so that the motors used to move the extruder along the X and Y axes are themselves stationary. One large timing (toothed) belt makes a circuit around the top of this cube in the shape of the letter H. This is a bit easier to see in [Arkadiusz's] rendered image found after the jump along with video of an early print test.
The Z axis uses two motors mounted along the bottom of the cube. These raise and lower the bead, instead of moving the extruder itself. All-in the printer should have a maximum object size of 30x30x30 centimeters. It’s being driven by a Smoothieboard, which was mentioned quite a bit when we were discussing using the RA driver board with a 3D printer.