In his quest to become an architect / engineer he has become rather obsessed with knex.
Perhaps unsurprisingly he is rather good at it, his understanding of structures and forces is remarkable.
I'm trying to get a video up on YouTube of his frankly astonishing ball machine which he had modified himself and fixed all the little anomalies he encountered along the way.
Until I get a chance to do that I'll present his 6ft7 ferris wheel (that moves)
Took him just under a day