This is basically what I do. Whenever a cool idea comes into my head, I put it into my list app. I have a list for projects (e.g., build a piece of furniture)

This is basically what I do. Whenever a cool idea comes into my head, I put it into my list app. I have a list for projects (e.g., build a piece of furniture), skills (e.g., woodworking), topics, and business ideas. I then review these lists periodically and when the time is right, they naturally move into my "Active" list in one form or another.