Can you see the progress you have already made? I can! Nice job with that.
Steve's got a pattern or two - toy cars or trucks I think - that are made from 2x4's. Those are pretty inexpensive. A number of folks check in at cabinet shops and the like and ask about getting scrap from them. I know some people who build staircases and they have given me a few pieces leftover of wood. Scraps from places like that can be plenty big enough for scroll saw projects. Even Lowe's or whatever might have some end cuts. Can't hurt to ask. If they say no, you're no worse off.