You've done so well with the variations to this design to make something so useful. Nice kitty!
Also another source of sheet magnets...many businesses hand out advertising magnets..and I save these and eventually use them...with my own glue. Usually tacky glue is not so good so I use a jewelry type glue.
I'm a recycler so I have found FREE magnets. Strip magnets are FREE in the rubber gasket in old refrigerator doors (I find these at our local recycling center...cut into gasket with razor knife and you'll find about 8 FEET of mag. strip...you do have to use glue..not self gluing.