Above, we stacked two IKEA bookshelves (hackhackhack) and attached them to the wall. The idea is that the shelves won't fall forward if pulled on by some foolish young person. Behind the door you can see that we've mounted a whiteboard/corkboard combination for him to record his triumphs.
He also needed a desk. He specifically requested a drawer. We looked at a local mid-century modern vintage place and loved much of what we saw there. But not, so much, desks. Iain liked one desk - teak, with a locking drawer and cabinet, both employing an old-fashioned skeleton key. He dreamed of the privacy of locking his things away. I dreamed of the nightmare of finding that key.
But in the end we bought him a simple, modern desk with two drawers. It's not world-class furniture but it will do for now. He added a lamp and some colored pencils to make it his own.