Andy, have a look in my album's at the Stirling Engine, this was built by my Grandson age 14 — he's now 20 and most way through his engineering apprenticeship. He had used machine's since around 12 – always start young ! but this was the first proper project and he made everything himself under instruction – a great way to teach and they have something to show at the end.
This covered turning, milling, drilling & tapping, knurling, screw cutting, soldering, filing, sawing, marking out, so an all round project.
Good luck with your apprentice. John

Edited By JohnF on 30/06/2018 13:56:34 spellings etc ! darn auto correct !
Edited By JohnF on 30/06/2018 13:58:28