Find some fun fur and cut about a 6 inch square (it can also be a circle if desired)

I used an iron on fabric, but you could also sew a patch into the back. Make the patch big enough to cover a good amount inside the tribble, and make a tab that sticks out for the alligator clip

The smaller ones should work right from the pin of the circuit playground w/ no extra fussing, anything larger and you might need a diode + transistor circuit. Though you could also use that if you wanted a stronger pulse.  Solder it up (I used some silicon wire) and wrap the motor in something to keep it from setting off the cap sensor (i used some gaffer tape, and hot glue on the lead connections).

Take some embroidery thread, and do a simple stitch around the edge of the tribble on the back, leave some long thread leads. Follow the "how to make a faux fur pom pom" video, but basically stuff it and pull it together using the thread, then tie it off on the bottom. You now have a tribble!