Sibianul,

It sounds like you've done your research. I can start pointing you down the right direction but you have some limiting factors in your design request. Mainly the 120mm/s speed request.

First, you probably want to consider a Cartesian printer (MendelMax most likely). That's not to say that a delta won't work, but a 30cm x 30cm x 30cm capable delta is going to be quite tall and most likely require custom arms. Don't let me convince you though...there are some big delta's that have been done.

Also, in order to print Nylon/ABS/Polycarbonate/PET etc. you will need a 30cm x 30cm heated bed. Luckily they have them: http://www.amazon.com/approx-KEENOVO.../dp/B00V81ZI70. You'll need a solid state relay for Arduino control of that bed though.

As for the hot end, you are correct, an E3D V6 or E3D Lite6 are very capable. The V6 has no PTFE in it so it's good for 260C+, a bit more than what you need for nylon. The Lite6 does have PTFE and it's good for ~260c. Everyone says 245c for the Lite6 but PTFE has a Tm of 365C and doesn't really start deforming until around 260C. The Lite6 is what I would recommend. Also, check out Polymaker PC Plus. I don't really know how it compares to Nylon but I've been printing some very strong parts with it lately. Granted, it's more brittle than ABS and probably Nylon.

Second...a laser diode should be a relatively easy addition. I just saw this thread a couple down that may be of interest. You might have to make some custom GCode to trick the software into controlling the diode instead of a hot end, but I know that Repetier Firmware just introduced CNC/Laser Engraver support in 0.92.8. Check out the "Tools" tab here: http://www.repetier.com/firmware/v092/

If I'm not mistaken, Sailfish produced those results because it had acceleration control. In reality, nearly all firmware allows you to tweak your accelerations and jerk these days.

Back to the design though....120mm/s is going to be very hard if not impossible to achieve with a Cartesian printer, but a 30cm^3 build volume is going to result in a large Delta. If it were me...I would use those 20x80mm OpenBuild profiles to start fabbing up a solid MendelMax frame. You really should call and price out a UltiBots MendelMax before going full custom though. http://www.ultibots.com/ultimax-3d-p...iy-kit-deluxe/