Just go to sleep the first night. In the morning you will have every sharp object Nature can provide poking you in the back <img src="/images/graemlins/grin.gif" alt="" /> Smashing large bones creates sharp shards. The trouble is Nature doesn't leave large bones lying around very long or theres a big beastie usually chewing on them. Lithic materials are usually plentifull, but it does take skill to fabricate. Your best bet is to buy a decent knife that won't fall apart, tie a paracord lanyard to it and yourself and don't lose the thing <img src="/images/graemlins/wink.gif" alt="" /> Then go out and practise making field expedient tools.