Enter

>load sand in slingshot
>try out newly-loaded slingshot

You grab a handful of sand and pour it onto the slingshot. You pull back the band and most of the sand falls off. You fire at the door in front of you.

It's mostly ineffective, creating a small cloud of sand. Where the grains hit the door, they created small holes in the door. You look through to see an identical room with what looks like an ugly gargoyle.