Sounds like you're eager to try a new technique so go ahead and try it out, but I just wanted to say normally any "sleeves" for cosplay are just armsocks/armsleeves, and they're just made out of tights or that kind of material (assuming you want a "skin" look. Other fabric is used for a metal/robot look). Making one of those out of silicone or rubber would likely get very hot and sweaty very quickly, and I can't imagine it'd be thin enough to prevent obvious wrinkles.
KuroNekoCon- '11 : Radcon-'12 : Akicon-'13 : Sakuracon-'13, '14, '15, '16, '17 : PAX West-'11, '12, '13, '14, '15, '16, '17 : Rainfurrest-'15 : ChibiChibiCon-'17 : RenCon '17
Shy Gal (Nintendo Fan Design)