I had a prusa mk1. 1.75mm filament. 5mm standard threaded bar for z axis. Red pcb heat bed and glass surface for heat bed. Direct drive extruder
Before this was the mk0. 3mm filament with geared extruder
I try to make suggestions that I believe to be well founded and safe,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions,
what you do, is YOUR responsibility.