I tried to assemble WH40K people at Dragon*Con 2009, but was unable to attract attention online. I saw a few Guardmen and Techpriests, but we wore our costumes and different times and never got together.
At Sakura-Con I found a Techpriest
, who says she plans to add on to the costume over time until she has a full exo-skeleton, which is a cool way to go about it. Reportedly her fiance was also around in a matching outfit, but I didn't find him.