Technic Advice

My kids and I recently built the Creel House and they expressed wanting to do more with transforming play features using technic bricks. THE IDEA: I'm designing our Halloween build and I'm thinking about a gimmick of a trap door that a claw/hand can come up and drag a minifig into the trap. Or even something where a piece of furniture comes alive and swallows a minifig before the furniture returns to its original position. (Think like the game hungry hungry hippos) THE QUESTION: Are there...