Carbon scrubber or other odor cleanser.

ah, you need intake and exhaust to circulate the air. it dosn`t have to vent to outside

Here....take a look at this.

Ryoko Builds a DIY Activated Carbon Filter - 30 Minutes, $30 Dollars - The Garden's Cure

i seen that seems like a great method but that is for a box if you have a whole room then what?

ya i built one of those also. another waste of money having to replace the cloth filter every couple weeks. i did make another that is a copy of a real filter and uses activated carbon. for about 50 bucks depending on your cost of carbon. i just posted it for someone