BUSINESS CARD GLIDER!
All you need are these ingredients:
-A pen or pencil
-A rad straightedge you got in elementary school
Step 1: Empennage
Step 2: Vertical Stabilizer / Lifting Surface
Fold each end up! This will be the tail section of your aircraft. I like to fold about 45 degrees, mainly because it's (a) stealthy and (b) it looks cool.
If your card has a natural camber, or bend, to it, fold away from the camber. If it doesn't, add a very slight one. This will provide lift.
Step 3: Payload
Apply paperclips. You're done! Now throw it!
There's a good chance it won't fly at first. That's fine, because now you'll have to tune it until it does. Slide the paperclips fore and aft, or bend the tail section up along the line you drew earlier, or fold the vertical stabilizers up a bit more.
Once you get your glider tuned, you can use the tape to secure the paperclips in place. Now go amuse your cat!