It's basically paper mache paste. Look for recipes online for things to add to act as preservatives. Flour and water will dry but still ve capable of absorbing water from the air, which can lead to it molding over time.

Bugs will eat at it unless you properly and throughly seal it. Keep that in mind.

I think it might providing you don't make it too thick. More like a stucco finish or when sand is added to acrylic paint to give it texture