Sensory mats - "Goo bags - recipe for goo. I've had it suggested to use an entire bottle of dollar store hair gel, but this is probably just as inexpensive, and you can make whatever VIBRANT colours you want." Letter writing with fingers or Q-tips.
A good idea for a small bathroom, under hanging shelves for things like cotton balls, cotton swabs, etc. Also great in the kitchen, for a spice rack over the stove. Just hang jars from bottom of the cabinet.