This is an easy one to do, nothing fancy just the basics -
5"
Proffessor River Song with Removable Helmet, Future Sonic Screwdriver
& Sonic Blaster
Proper Dave with Helmet (It can be done with a turning mechanism so
that his face can be changed from human to blank to skeleton.)
12"
Proffessor River Song
Roleplay
Future Sonic Screwdriver
Sonic Blaster