Modified kraken home made 3d printer

im designing a 3d printer on solidworks my goal is 800 mm in X 400 mm in Y and 500 mm in Z

im open to suggestions.

my design is based on the ultimaker 2 for x and y motion.

z motion is up for opinions.

im guessing im going to need a board that is compatible with master and slave for marlin.

gear box steppers yeah or neah, and what sizes.

the linear rods are going to be M12 with LM12LUU bearings and some type of radial bearings for end support.

motion for x and y is belt driven by gt2 pulleys.
all motors will have 18 tooth gt2 pulleys and the rods will have 36 tooth pulleys.

so i have 1:2

Z axis is set up with anti backlash lead screw M12 3Pitch

hot end is based on the e3d kraken and the heater blocks are based off of the v6 both made from copper then nickel plated my chromed as well not sure about chrome is necessary

im hoping it wont have any sag on the x y

let me know in the comments on your thoughts