Vanilla items block

What if you had a procedure that would take a vanilla block or item and you could change properties and texture of it, and make a new item? In my jojo mod, there’s a thing where a guy has a mega powerful fishing rod that can’t disconnect unless you take it out of your hand, and it wouldn’t be an insanely hard addition, but actually doing the fishing rod seems... difficult. If there’s a way to do this already pls tell me because this is one of the last stands I have to do before my next update but if not then can you guys add it 2020.5/.6?