Eh, personally I'd get them a box of nice marking pens and computing paper.

Marking pens (these are my favorite) are very useful for engineering. They make clean, dark marks on paper, and since they are ink-filled medium instead of traditional ball point pens, they can write on a lot of the things much easier, such as metal parts in a shop.

Computing paper is something that a lot of engineers love, and those that don't simply haven't used it yet. Its slight green hue makes it easier on the eyes while writing notes (and makes it stand out in a stack of papers), plus the grids make it easy to write not just words, but also make diagrams. My go-to is this one.