Giving my daughter a real hammer felt like a big step. I hovered for the first five minutes, then sat down on the step with my coffee and watched her concentrate harder than I had seen in weeks.
Hammering is deeply satisfying work: it is loud, it is physical, and it has an obvious result. For a child who has too much energy and nowhere to put it, a log slice and ten nails are better than any toy.
We started with 'hammer a nail anywhere' and it slowly grew into leaf pinning, then yarn wrapping, then a whole afternoon of pattern making.
Tip
Wide-headed nails are much easier to hit than thin ones, and a proper small hammer (not a plastic toy) actually makes it safer, because the child does not have to swing hard. Stay close for the first few sessions, then sit back and let them work.