It's not the most obvious tool, but I use sticker spray all the time, it's so versatile, just recently I used this one tool to create a piece of art that looks exactly like a real pencil drawing, had a few of my family and friends fooled with this one.
It is the nature stamps, 'WHEAT'. You can create amazing tone by keeping it set to autoflow and I love the grainy nature of it, even the tree branches were created with it, all but the tiniest top branches (where pencil) 99% of it is sticker spray.