Dual Z axis support for the Ender 5.
It keeps the original printing volume (and actually it could gain a couple of cm in the Y direction), and does not need a second motor.
I tried to make the design as simple as possible, without the need to modify anything on the printer other than removing the now unused parts.

Part list:
1 - GT2 timing belt 6mm 852mm
2 - LM10UU linear motion ball bearings
1 - 8mm lead screw rod 395mm long with T8 nut (the original one is shorter but it can be used by printing the extender)
2 - 10mm rods 395mm long (NOTE: the original ones are longer and they wont fit inside the frame so they have to be cut, so if you want to be able to revert the changes you need to get the 4 rods)
4 - 8x16x5mm 688-2RS ball bearings
12 - Bolts M4 15mm long
14 - Bolts M4 10mm long
2 - Bolts M4 30mm long
8 - T nuts M4
20 - Nuts M4