A hotkey to tighten low sagging cables / pipes would be 
I'm imagining 2 scenarios here:
- While holding the cable, press a key to tighten, then put it into the machine
-# In this case an additional auto-tighten hotkey would be beneficial, since putting cables on the ceiling would still have them without it sag. Auto-tighten would then tighten the cable after it was placed
- (much better imo) A hotkey that only shows when hovering an already fully attached cable. This would beat low sagging cables over long distances and ceiling cables at once while also not giving an overwhelming amount of hotkeys during cable placement