I made stuff, and unusually am quite happy with it. The design's heavily inspired by a Blood Angels one by Jerac but sticks to official parts apart from a plated grill from Chromebricks. When I've got the design finalised including the smokestacks on the back I intend to recreate it in LDraw, but don't hold your breath for that.
Those award ribbons were part of the larger-form Scala sets LEGO did about ten years ago. Asides from that the parts aren't too uncommon on the red one... the blue one does more "illegal" things with the build, such as ramming translucent rods through Technic half pins to make the multi-melta and detaching old-style pipes for the missile launcher. Plus I preferred the body higher than the Games Workshop Mark V design.
Next on the agenda is one in black (possibly as an Iron Hands successor chapter) and working out how best to do a lightning claw. What surprises me is that despite the old Sideshow Space Marine statues there don't seem to be large-scale models of dreadnoughts available either from GW or licensed third parties. It'd be such an easy way to sell to folk like myself who appreciate some of the Warhammer 40K fluff – mainly Ian Watson era, but Graham McNeil's recent Adeptus Mechanicus books are interesting – who aren't wargamers.