Chinese designer Yuchen Liu has come up with the concept for the Bottle Cap Sharpener – a pencil sharpener that is built-in to a standard-sized bottle cap that screws onto the top of most plastic or glass bottles. When sharpening the pencil, all the shavings are collected in the vessel of the bottle, reducing the mess that comes with pencil shards and lead bits. This type of sharpener would be put to good use in schools where shavings litter classroom desks and floors. Once the bottle is full, simple unscrew the cap and toss out the shavings – or, if you’re the artsy type, use the collected shavings to produce some kind of scrapbook masterpiece with an unexpected material. Either way, it’s a clever concept and a great way to practice being green (by re-using an otherwise useless plastic bottle).