You guys are over thinking this project and getting way, way too complicated. Why reinvent the wheel?
Here's what you need:
1. A cat. Hand raise it from a kitten and train it to do a simple task.
2. A wooden cooking spoon. Your wife probably has one in a drawer in the kitchen. Heck my wife probably has four or five. Take one, she won't even notice it's gone.
3. A rolling pin. Once again look in the kitchen. This she might miss it if she bakes much or uses it for disciplinary purposes. Virtually any cylindrical object will do.
It's simple. Cat catches mouse. Cat places mouse on spoon which is cantilevered over cylindrical object. Cat steps on spoon handle. Mouse is launched. No fuss, no muss, no bother. Sure the cat is going to eat an occasional mouse and perhaps torture a few but you have plenty of mice. Training the cat is the most difficult part but it can be done.
After several months of training I was able to get my cat to do it. I was just having him toss the mouse vertically, mostly for my own amusement, but I'm sure that you could adjust the angle to achieve a different trajectory.
