I'm putting together an Ordo Hereticus Inquisitor costume for a future convention. I'm reusing some props and clothes from my Commissar costume, like the nifty coat and probably the Bolt Pistol.
So here's a chainsword I'm making, which I'm designing with a generic look so it could be used with almost any Imperial outfit. I'll affix a removable Purity Seal with the seal of the Inquisition to it for the purposes of the Witch Hunter costume.
The core of the sword is two pieces of mahogany glued with wood glue. Around that is a layer of blue camping mat foam, which you can see in the teeth. I used cardboard for the outermost surface, with a simple plastic skull for the pommel, acquired at a conveniently-placed Halloween store. I love this season.
It will eventually be painted with a black Krylon undercoating and acrylics, most likely with the yellow/black warning striping down the body of the blade. At some point I will also add more detail to the motor housing and an Aquila badge to either side of the blade.
3/12/12 EDIT: Behold, the finished product. I used warning stripe tape on the body of the blade, obtained from a hardware store catalog, i forget which. The winged skull is cardboard painted with silver acrylic and then decorated with black sharpie, like my other skulls, Aquilas and so on. I'd tell you approximately how long it took to make if I knew.