Your cats likes windup toys but you are too lazy to keep winding it up... Mod it...
Things you need;
* Toy of your choice
* A playstation vibration motor or similar
* A casing that you can install motor in
* Solder gun
* Glue gun
Make a cut at back stitches of toy and remove the original mechanism, don't make it big since we are going to seal it back again.
Install the motor into the casing and then shorten the casing with some pliers etc. (just make sure the vibration weight is not touching front or sides and can move freely, that will be enough)
Solder the battery to the motor and solder the switch in between.
Remove the fibers inside the toy, install the tube, facing forward and battery after. Put the switch somewhere you remember. Stuff the fiber back in, making sure the toy is balanced and in shape.
Seal the toy using material of your choice, I used the glue gun in my case
. Just make sure you use high capacity alkaline batteries so they don't run out fast.
Toy is ready to go, press the switch and watch it roam around.