I've knocked up some BUAs from some stuff I had in the 'Use It One Day' box. The tower blocks are nearly all kids play blocks with some roofed housing made from balsa. The resin country cottages represent villages. The brick factory, there's always a brick factory, is another play block with a dowel chimney. Painted grey and drybrushed with white. The windows and doors I painted quickly with little regard for right-angles and other such nonsense.
They're mounted on old gift cards with a PVA/gravel mix. Painted green/drybrush yellow for a bit of colour against all the grey. Nice and quick to knock up and ideal for the job in hand.
UPDATE: I'm now following AI's blog, it's ace!