Hmm. That's a tough one. A pocket knife would be ideal, but opening, closing, and use would be difficult. Maybe a higo no kame? That little tab on top is used like a lever to open/close, and it's a friction lock so no manipulation. Holding and using the knife might be hard too though right? Did you have problems using a knife? I'll get him some play dough too. He's been my best friend for a long time. We were on midnight shift together for 8 years. Thanks for your help!