I use my friends router, my first build, which is not a mill, but is very precise/0.01mm and still continues to surprise me/

Ok, i get it. I haven't thought of that. So what you say is mill a bed, and then one by one fix them, flip them and mill them. Horizontally yes? Sounds better than lathe and simpler. or you mean the part to be vertical and do it at once? Wouldn't it vibrate like that?

As far as i understand you mean to make all this vertically, so i open the vice

PS:
The 6mm goes into triple bearing, so not that the diameter is so important as the center line of the piece, cause it must rotate dead on its center/2.5mm/ other wise when the bearings are encased, it will try to move them differently and friction will occure