The weapon is a twin-linked devourer, made from spare gaunt and warrior / tyrant arms and weapons. I have seen other conversions of this weapon that use the fleshborer hive arms (legs?) from the Tervigon / Tyrannofex kit, however I wanted my version to still be a recognisable version of the original weapon, simply up-scaled.
The bone armour plates were painted using my usual coats of red, white markings, red ink and gloss varnish. It is quite time consuming but I'm always pleased with the results - particularly with the bigger creatures!