You can buy resin casts of designer Harry Allen’s hands, which are also easily mounted on the wall. 

This one can be used for more surreal applications. You can create a human arm sconce hallway similar to the one in the classic Jean Cocteau 1946 film Beauty and the Beast, La Belle et La Bete>>

 
Get hands from Generate Design>>

If you want a cheapo version, a package of plastic fingers is available here, from goofy product company Archie McPhee>>