When it comes to FDM-based desktop 3D printers, the majority of them all work with the same basic Cartesian format. An extruder moves along an x,y and z-axis in a grid-like format to slowly fabricate an object one layer at a time. In addition to Cartesian-based systems, delta-robot systems also exist, but are used less commonly. We have not seen many FDM 3D printers stray from these two methods, besides in a few rare machines, most of which have yet to be released.
Hack A Day, the website which redefines hacking as “an art form that uses something in a way in which it was not originally intended,” is in the process of hosting ‘The Hackaday Prize” competition which is pitting 50 semi-
One of the semi-finalists is a man named Tyler Anderson, who has created a 3D printer which functions like none we have ever seen before. The printer called ‘Theta’, which he has been working on for quite some time, uses a staggering four different filament extruders. The Theta printer, hence its name, uses a polar coordinate system, by which the build plate rotates as the extruders move and print along the radius of the circular plate.
The printer, which features 10 stepper motors, is quite incredible in the fact that all four of its extruders can be printing different filament colors or types all at the same time. This means that they can work together (if the the project allows for it) to print an object which is made from multiple materials and colors, in a fraction of the time it would take a traditional Cartesian-based printer to do the same. We have seen numerous dual extruder 3D printers in the past, but for the most part these extruders only function one at a time.
“The Theta printer you can use all four extruders running at the same time to either print four different materials or you can have them all printing the same material four times as fast,” stated Anderson.
Some additional advantages to the polar coordinate system is that there is less moving mass, equating to better acceleration as well as print speeds. Because of the smaller movements of the build platform closer to the 
As Brian Benchoff from HackaDay has pointed out, such a machine could be used to mass produce four of the same parts at once. This could be done simply by programming each extruder to print the same object as the build platform moves under each extruder in exactly the same orientation. Basically the Theta printer would be able to produce four of the same parts in the amount of time that a typical 3D printer would take to print just one. Talk about efficient! Anderson even alluded to the possibilityof adding 4 hot ends to each extruder platform, equating to a total of 16 different extrusion areas.
As for sending models over to the machine, the Theta printer is actually compatible with any Cartesian slicer program, as well as regular RepRap software. Let’s hear your thoughts on Anderson’s creation in the Theta 3D printer forum thread on 3DPB.com. Check out the quick video below where Anderson shows the Theta printer in action.
[Source: Hack A Day]