Drawknife, rasp, knock file. That makes a bow.
I hear they have been made with rocks before! It's all in how pretty you want to make them. I have seen works of art from skilled craftsmen and functional long lasting bows from tool makers. I own some of each.
My advice is start with what you have. Learn to use each tool well to get your desired results.
If I could only have one tool, it would be my farriers rasp. I can hog off wood when needed and make very fine tillering adjustments with it. It's all in how you control it.