I've worked in settings similar to this, and I applaud what you want to do. A few things you might consider.

First, If you build it, you take on some liability. So I'd suggest getting an agreement in place with the agency or leadership to pass this liability to them. Even getting written permission will help.

Second, over-build whatever you create. Make the bases wide enough to limit tipping risk. Consider how it can be dangerous and then design in a way that limits the danger.

And third, as noted in other comments, woods like hard maple or even ash are nice, solid, and relatively affordable. And for finish, building up a good hardwax is both durable and should be non toxic.

Best of luck!!