Would you print me this equation?
I have found a couple of interesting tools. On one hand, Wolfram Alpha allows you to download any generated volume out of your equation, but you need to have PRO account. It seems you can have free PRO account for a couple of weeks, but later you have to pay a monthly fee. I did not explore that route any further.
The other is a piece of software called K3DSurf that does the job for free. It is interesting though it did not work in my Mac, not even after installing Qt3, but it worked in Windows XP. It is worth a try!