I'll take the mechanical part. I actually have a mould for a rock about 12"x9"x6"(30x24x16 cm) "someplace" in Georgia, US. (OK, I used to get bored at work and had to make myself look busy.) I can cast another no sweat. Silicone rubber mould. Use a rigid polyureathane foam for the part, can cast with a cavity or embed the electronics then air-brush a finish. Foam will exotherm to about 160°f/ 70°c during cure. Good insular qualities, same density as soft pine wood. Movie studios use this for making special effects 'boulders'. I use it for model trains.
If this doesn't get any governmental attention to this site, I don't know what will ... I better put an extra layer of tin-foil in my hat now...
Я не знаю ничего, ничего!!!