I was talking with a gunge buddy about messy pies the other day and he brought up making pies out of dough. He says these are used in the UK a lot and it's basically a batter made of flour and water poured into a messy pie crust.
I'm really into messes that don't clean up easy, and he says this one sends you to the showers for a while to scrub and scrub to get it all off. Humiliating and hot!
I know that water and flour can be a gunge no-no because it turns into hard little balls that stick to your hairs. But this sounds like it might be doable.
It sounds like fun especially with the extra mess of the pie crusts. It is generally regarded as pretty bad clean up because of the gluten (clue is in its name). You can mix it to anything between pourable batter to mouldable dough.
Here's some pictures from online about the world custard pie throwing championship held in the UK that uses doughey batter pies made of flour and water.
Supposedly you have to scrub a while to get all that off, which is how I like it!
Flour and water is potentially glue only if you let it dry. The only time we ever had problems was one time sitting around under hot lights taking pictures. We use lots of flour now with wreckless abandon - dry, wet, with oil. Oil helps.
The 'secret' of extreme mess is actually just keeping it moving...preparation for the worst and... confidence.