Making a Z axis on a 3D printer

I’m trying to build a new 3D printer, using the CoreXY concept, and mostly built using these files and site:

However, the Z-axis is not really working. So I started to work on my own.
As I had some parts to lay around from the FirePick project, I thought I’d use the bottom aluminium plate.
It’s cut perfect to size to fit one of the M5 threaded rods I intended to use, in one of the screwholes in the middle.
I’ve tested the 3DPCB with 3 nema17 motor and the same time, running smoothly and perfect. Each stepper has an M5 threaded rod
right on top of it, using either flex coupling or some rubber hose.

I designed the parts in the DXF file, so the plastic I needed to print was fitting perfectly in the aluminium plate.

The parts printed perfectly and now sits on the alu-plate

I still need to either fixate the M5 rod in the top, so the axis doesn’t wobble, or print some 8mm rod fasteners and make an LM8UU part to
make the alu-plate go straight up and down.
But for the first test, I’m happy if it runs smoothly.

Yay, images:

OpenSCAD render of what my printer looks like

OpenSCAD render of what my printer looks like