This means that I have to dismantle the damn thing again and take care of the wire slack and resolder the laser leads so it fires properly. But at least I know the theory works properly. For about thirty glorious seconds, I had the laser firing and the R2 roaming around the floor of the apartment.
Speaking of the floor, it's a hazardous mess right now - littered with screws, washers, and little shavings of plastic and metal from the rather brute-force methods I used to get everything to fit nicely.
I also inhaled more melting plastic during the fabrication process of the "concealment hatch", which sits on top of the laser switch and hides the fact that there's an ugly modification underneath. It'll be a heck of a race to see if I finish this project before I die from all the toxic crap I've introduced into my body.
Photos and a proper documentation of the procedure will be posted when I get it done.... in other words, don't hold your breath. (Or, actually, do hold your breath - the plastic fumes are still a bit rich.)