first of all I'm Hungarian so sorry for the mistakes. If you want to play whit your cat ,you can use this. Its easy so you can make this really fast ( i made it in an half an hour) its price was low exactly 1650 Hungarian fornits ( 9 USD). in the next step I only wirte "some Lego block" because it may vary.
Step 1: Get the Materials
-some Lego blocks
-battery case whit two AA batteries
-plastic tube (short)
Step 2: Curcuit
Step 3: Place the Curcuit to the Lego Case
grab the Lego blocks and build a case that enough wide,tall etc. important! the circuit can be placed in the case