I've played around with the idea of showing the armament carried by the Tunnelers to tie them in with the Chimera.  To that end, I've modelled one showing the left over Multilaser from a Valkyrie and a sponson Heavy Bolter from a leman Russ.
 


Additionally, I've run a trial paint scheme on one using a black undercoat, a spraying of leadbelcher followed by application of blu tac and a coat of Army Painter Dunkelgelb.  I'm going for a more industrial scheme for these rather than my standard black for Praetorian armoured units.

More tomorrow.