The book was the size and style of a Dr Seuss book with an orange cover. It contained fun things for kids to do ie: curly paper book mark races ( something about Willy?) , rooting a sweet potato and making a newspaper tree. I think it may have been the same illustrator as the Seuss books. It would probably have been published in the 1960″s.
Could this be Robert Lopshire: The Beginner Book of Things to Make: Fun Stuff You Can Make All by Yourself? There were several editions of this; an early one was called ‘How to Make Flibbers’.
Agree! The Willy project is A Creepy Wlly. Fun book.