As you can (not) see, I used 3x 8mm nuts and a ziptie inside a ball of kneaded 5min epoxy and a ziptie round the whole to hold the z-axis
This seems to work ok for a bootstrapping. The rods are a mess, not straight at all and will wobble quite much.
As a result I had to leave the motorbrackets unscrewed-down so they will move a bit with the rod. I can not see that it affects the printing yet but.....
I will look into driving the z-axis with a belt.
As for the belts they are GT2mm and the pulleys are 36 tooth
The back is an actual breadboard and so is the bit holding the extruder
The extruder is sitting on a bit of breadboard that is cutted a V of 45deg to allow for the mounting of the extruder
the breadboard is screwed to the plate with self tapping 25mm platescrews, but I predrilled holes for them on the edge with a cordless drill by hand.
All the bootstrap parts will be replaced with printed parts or machined ones when I will find the time to do it
And the first build: I had to adjust the trimpots of z-steppers while printing so there are imperfections in the bottom 5mm. The rest is ok for a first print.