High quality mechanical pencils with a rigid metal sleeve that makes it perfect for technical drawing.
Mechanical pencils are a great upgrade to the standard wooden pencils we use all the time. They allow the mechanical pencil lead to be extended from the pencil whenever it gets worn down, via some sort of retracting mechanism, meaning you never need a sharpener, your lines never vary and you never need a new pencil.
You can get all different types, from luxury mechanical pencils, to technical drawing mechanical pencils and everyday mechanical pencils, all serving a different purpose. You can also get different lead thickness, and some have built in mechanical pencil erasers.