You're definitely doing God's work here. One thing that I struggle with is when you hover over an interactable, its connections are highlighted, but the highlight color is just barely discernable.

Another somewhat more advanced thing that I'd like to see would be a way to click on an interactable, causing its highlighted interactables to stay highlighted while I jockey around the contraption to get to see what it's connected to and then click on whatever I want to connect it to.

If we're really dreaming... I'd like to be able to give text labels to the parts, and when I hover over the part, I can see (as a tooltip) the name of the part and the names of the stuff it's connected to.

If we're really, really dreaming... I'd like to be able to just type in the name of the thing I want to connect to rather than having to drag to find it.

If we're flat out delerious, then if I break my creation in half and weld it back again, it remembers the named connections and puts them back together.