I took my older acrylic body HICTOP Prusa i3, took it apart and with some more material (2020 extrudes, smooth rods, and a threaded rod, and some more belt) assembled it into a coreXY printer.
Everything is printed on my other customized HICTOP (Aluminium) printer. I am still tuning the printer and it seems to be very easily able to print at 0.05mm layers and 140mm/s print speed. I don't plan to run it that fast at all times, but it is quite impressive to watch. Now I understand why people use 3.0mm filament since 1.75mm needs to be extruded really quickly.
Update: Version 2 is completed and is here: http://www.thingiverse.com/thing:1829772
The maximum build area is about 360 x 350 x 360. Right now I cannot find a big enough heated bed to cover that area (and probably need to upgrade the power supply as well and add more cooling to the transistors on the motherboard). I'm using the HICTOP original heated bed that is about 220 x 275.