Hi Mark,
Mine just has a two position switch that breaks the red wire in a long servo extension, and no film cannister.
The socket end of the extension was connected to a 4xAAA battery pack, but that had corroded right up to the plug, so I've taken that out, and will probably need to replace the extension too (which I've also taken out for now, along with the switch). I guess that was plugged into the receiver when it was in use and the charging process involved replacing the fablon - maybe it can be restuck a few times, I don't know.
Ideally, I want to be able to change the battery pack and crystal easily. I'd pictured putting the receiver in front of the mast, but I'm not sure where I'd route the antenna for a 40MHz receiver (which is my preference). It apparently had a receiver next to the servos, yes. I guess the antenna came out of the stern somewhere - possibly through one of two grommets set into the stern, and went up the aft stay, if that's the right term (adjustable bit of string at the back that runs to the top of the mast).
Hopefully I won't run into someone else on the same channel too often, so just taking some fablon with me could be the answer for crystal swapping. I'd still like a hatch for battery access though. I'm not going to race it, I just want to sail it for two or three hours at a time. Swapping packs every now and then seems best.
I picture a small tupperware box, or similar, maybe with the bottom cut out, probably set into the larger hole in front of the mast. I'm not too sure how to seal round it at the moment though, and it will have to be quite a small box, unless I cut the hole in the deck bigger.