Well, the Cleaner Ak seems to have a 2L bottle of fuel taped to the side of the mag/magazine well, with some hose-like tubing connecting this to something that is either a valve/gauge, connected to bent copper pipe with a lighter/form of flame attached to it or an extended blowtorch, linked to the fuel pipe. That should be pretty easy to source/attach (you can't go wrong with tape!), just make sure it doesn't work, or we might have to alert some local agents about a cleaner threat XD. Try some burlap wrap around the stock or tape wrapped on the grip, gives it an apoc look and also should improve comfort when holding it !
I was also wondering for the watch, if a switch like this:
http://www.modeltrainsoftware.com/3v.html may be able to be incorporated into the watch to allow the user to turn the power from the cell off/on, therefore saving energy and also keeping the internal components housed in the watch without needing to take them out. I going to head to my local electronics store tomorrow to see if I can pick up anything similar, and if I can get a solution going for a way to include a switch.