Headcanon: Since Jay is an inventor, he's of course not one to listen to directions and instead goes with what his heart tells him.
In S3, him and dad talk about weird objects that they can build with. And in Shadow of Ronin, he builds four functional jetpacks, yet he couldn't put the right word to exhaust valve.
He makes functional things, he knows a useful item when he sees it, and can visualize a plan. BUT he makes up names for parts (like his dad), does not know the name to parts he uses most of the time, and usually doesn't have blueprints to show the building process.
That be said, Jay Walker is unironically a Master Builder in the cartoonverse. And more importantly-
A feral inventor.









