Waterproof stains for outdoor kids toys
Polyurethanes are fine since they're on all furniture &amp; all the kids are plastic poisoned anyway, but the poly's don't last to long outdoors. I'm a huge fan of One Time Wood Protector &amp; it's completely different, lasts much longer &amp; just needs to be re-coated &amp; not stripped or sanded at the end of it's life. But, it's UV cured so the Sun has to bake your awesome project for a week before use &amp; abuse.

Of course, ask One Time about your intentions &amp; concerns...it's got an unlimited shelf-life so you just keep it &amp; use it as needed. I've only used it on a 2-car garage door &amp; multiple outdoor furniture items &amp; I stopped licking &amp; chewing on non-food products a few years ago, so I can't speak to its flavor or ingestion effects. Though, I was tempted.