After an unsuccessful tourney with Thousand sons I have had it hammered into me that Plague Marine are a much better choice for your points.
As it happens I had bought some of the awesome forgeworld Death Guard conversion sets and did some concepts for special weapon troopers awhile back.
crappy sketches of marines with 'plague gun'
So I started to tinker about with the FW Death Guard and found that using parts from FW mk2 crusade and mk3 Iron armour sets from an abortive Blood Angel sternguard project made them look wicked cool! I also wanted to make my special weapons into 'plague or bile' gun which could be used as Flamers or Meltaguns, one spraying the area with corrosive pus and bile and the other concentrating it into a jet of slime that will decay armour in seconds.......or something like that, plus they look great too!
Rear view of 'plague or bile' gun
Complete with 'sack of pus' and flayed face!
I have made minor conversions to the aspiring champ and troopers making the boots into hooves as per the classic plague marine look and making the tri skull symbol on the back of the powerfist.
The special weapon trooper had a bit more done on him. I started with the Cadian IG flamer and fuel tanks. Gluing the tanks on to the chaos marine power pack and then connecting to the weapon with a hose using guitar wire. I sculpted the 'pus sack' and flayed face using green stuff and the hose connecting them is off a Tyranid weapon(I can't remember which one). To top it all off I made some sores out of little balls of green stuff.
I still need to make 2 more troopers and another 'bile gun' to make the squad into the sacred number of 7....and then the second squad of 7, just waiting on some Phobos pattern bolters from FW before I can proceed......................
