This has to be my all time favorite infant "toy". I used it at one time or another with all my boys.
(Infant Acetaminophen Bottle)
It's already made to be childproof. The container is the perfect size for small hands to hold. The top is just the right length and texture for abusive gnawing. But, here's the kicker ...... if they happen to spit-up in the midst of chewing on it, they just suck it right back down because of the bottle-like shape of the lid.