Every new idea is just a restatement of old ideas, or sometimes it’s several old ideas combined into a new one. Collecting ideas as you go along is a great way of mining new ways of thinking of things.
I use an Idea Bank to hold my ideas so I can use them at a later time.
For a long time, I’ve used a plain old folder to hold things like quotations, objects, articles, pictures and other ephemera. What I like about a physical folder is that I can pull the objects out from time to time and physically associate them with one another as I try to create new ideas out of things I’m interested in.