Best pencil-top erasers according to redditors

That's very well done for a 6 year old. I've worked with kids that age for years and they're usually pretty sloppy when it comes to motor skills of this sort. Well done!
Edit: They do freaking come pre-printed! Kids these days get golden tickets like this handed to them

http://www.amazon.com/Moon-Products-Smiley-Pencil-Erasers/dp/B003U6VVJA/

Amazon has little brain erasers. $10.99 for 36...
http://www.amazon.com/Brain-Shaped-Pencil-Top-Erasers/dp/B004EV59HA/ref=sr_1_1?ie=UTF8&qid=1342031278&sr=8-1&keywords=brain+erasers

http://www.amazon.com/gp/product/B003U6VVJA?ie=UTF8&at=&force-full-site=1&ref_=aw_bottom_links

Colored safety glasses as party favors!


I loved the "touchable" test tube bubbles when I was a kid, perfect for your theme!


Plastic magnifying glasses


Atomic Super Balls!

Eyeball rings

Microscope center piece.


Brain pencil toppers


If you have time to make cookies!

If you have time to make jello




You can use these bio-hazard bags as goodie-bags! :)



I tried to look for everything in packs of 12 or more, so hopefully these help you! :)



item

https://www.google.com/search?q=japanese+pencil+topper&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiMwJfqmP3MAhVG_mMKHfK2BvgQsAQIHA&biw=1002&bih=890

http://www.amazon.com/1-X-Pirate-Pencil-Toppers/dp/B000CIO54C for another example. I don't have a good sense of the hole size in your pic, so I'm just guessing that it's about the size of a pencil...

BRAINS!!

Our gaming group bought these, they are a little big and bulky for a small filler games, but makes it so much more fun when we play.

These are cute erasers I put in my prize box (as a teacher) but that I bet kids would love for Halloween. (Pack of 50 under $10) https://www.amazon.com/dp/B00ZP8Q6D2/ref=cm_sw_r_cp_apa_i_JwLRDbE1BERG5

Or these animals clip onto things and were an even bigger hit (but cost way more -- 24 for $13) https://www.amazon.com/dp/B019J7EK6O/ref=cm_sw_r_cp_apa_i_nzLRDbX1E9Q75

This Is the closest I could find.