Algodoo

Inspired by UnityDogGaming04's Wind Tunnel.

This one's much more sophisticated.

TO USE:

1. Set the Spawn settings by editing the boxes
2. Set the Target value to however many air molecules you want
3. Configure the velocity and reversed mode however you want, even while the scene is running if you want!

BONUS: You can set the target to 0 to start over with the spawn settings, or you can do something like 250 of one then 250 of another.

The possibilities are endless!