@ Nikolas. cheap hairpins only for confirmation of correctness of design. If design successful then it is possible to buy expensive hairpins. From my experience: I made long ago 3D a cutting torch where leading screws were from construction hairpins. They work perfectly till this time.
Basic racks are in any case necessary. such as here [forums.reprap.org] or similar.
Or you think you shouldn't be engaged in this design?
The inverse kinematics on this are pretty close to the kinematics for the Rostock. However, the carriage rotation in coupled with its translation so you will have to do one trig calculation for each arm to adjust for that. That should be no biggie for an fast ARM processor.