Pipe Cleaners & a Colander
Two packages of pipe cleaners in various colors and textures ($2) plus one plastic colander from Dollar Tree ($1) equals twenty minutes of one happy toddler. We played with the pipe cleaners by bending them into shapes and then showed him how to poke them through the holes in the colander. He would squeal with delight every time he got his little hands to finally push that pipe cleaner through a hole. We did this right after he got up from a nap so please pardon the Crazy Hair.
Another post-nap activity was pom poms and a muffin tin. A gigantic bag of pom poms in tons of sizes and colors was $5.99. We separated some of them by color (this used just a tiny bit of the pom poms in the bag), put them in a muffin tin, and turned him loose. At first he seemed a little uncertain, but as you can see, he warmed up quickly and eventually made his own pom pom "ball pit".
Not that I have any experience with this phenomenon.