3D Printer Mendel Type Small (relatively)

This is my next homemade project for 3D printer.
Single homemade hotend or E3D compatible - 0,4 mm nozzle, bowden type extruder.
400W PC ATX PSU.
Electronics - Mega2560 + RAMPs 1,4 + Full_Graphic_Smart_LCD_Controller + 5 NEMA 17 motors. Malrin Fimware.
Expecting very small or none backlash effect with 5 mm rods for Z axis.
Working area with 220x200x3mm glass- XYZ - 220/186/148 mm;
Manual control for 40 mm fan for hotend/always ON by default/ and manual control for 30 mm fan d