Extensions or plugins for plumbing pipes and electrical wiring

I’m in agreement with you on 3Skeng extensions, they seem rather useful, but the associated pricing isn’t justifiable in my case.

VBO Piping
The Engineering ToolBox
Draw pipes from lines PRO
Eneroth Pipe
PipeDraft Extension for SketchUp, but it’s been depracated

I’m sure you’ll find some more if you took the time to look.