Is it safe to drill a hole in an Apple TV (3rd gen) remote?
Have a look around the web for disassembly. From a quick look, it appears there is room to drill a hole below the battery for the silver remote. 

The newer generation black remote is much more contained, but there is room in the bottom corners of the remote below the battery. 

I'd recommend disassembling and removing adjacent parts before drilling.

Update: Very late reply but for the TV2 remote it should be an all-aluminum body below the battery. I drilled a 1/8" hole through the bottom left.