So the not-so-little 16 year old sat down heavily on our (steel-
framed) bed and snapped one of the slats. It looks like it was a weak
one anyway as it had a knot where it snapped.

Has anyone had any experience of these things? My first reaction was
to shape some timber to replace, but normally these things are shaped
and sprung so maybe that won't work. On the other hand, I'll bet
almost anything that it's near to impossible to get a new 'real' one
to fit a king-size and, as it's only the one slat, how bad could a diy
job be? I've no doubt someone will tell me......