Introducing the Japanese Hair Bun Sponge!
Let me tell you, I AM IN LOVE with this little gadget.
I came across this on Ebay (you can search Hair Bun Sponge), it sells for about $2-$3 for 2(1 large 1 small).

How to use it:Here is a video link on youtube of a tutorial I found:
Tutorial1. Tie your hair up in a ponytail
2. Split open the sponge like below
3. Slip your ponytail into the hole and bring the sponge to the crown of your head where your ponytail begins.
4. Close the opening of the sponge by pushing together the sides so that it looks closed.
5. Now bring the sponge with your ponytail still inside the hole all the way to the end of your ponytail.
6. Roll your sponge inwards - keep rolling until you reach the beginning of the ponytail.
7. Then bring the two ends of the sponge together by folding it.
Now you have your perfect voluminous sponge!!!

Here is how it looks on my hair:
It gives alot of volume to your bun because of the tool being made of sponge material.
If you have layered hair like I do and some strands stick out like mine below, just clip it back in with a bobby pin or mini clip and hide it in the bun.



I wear this to work all the time and it stays put so well!!!
You dont need any clips/pins/hair tools to keep this up, the sponge basically does it all.
I highly highly highly recommend this!