Don't know if anyone is still interested in this
Here is all you need to make one.
Lowes or Homedepot:
2 Home heater ducting end caps.
The bigger one will be the outside diameter of the filter. Get one 2 inches smaller the the bigger one. So a 4" and 6" or 6" and 8".
1 8" to 6" adapter.
1 6" duct collar.
3 6" hose clamps.
3 8" hose clamps.
1 roll chicken wire. 1/4 inch. Fencing isle.
Somewhere they sell fabric (wallmart has a fabric section):
1 bag Polly fill (for stuffing .)
2 yards quilt batting. (to keep carbon from falling through chicken wire.)
(I thought this was funny so I just copied and pasted it)
You could use hose, but depending on your wife's tastes, it's probably not a good idea to let her catch you sneaking out of her closet with her 60 dollar victoria secret thigh highs.... Then you might say something stupid like Why the **** are you spending 60 bucks on hose? And you might end up geting in a fight and sleeping on the couch.... <cough> Anyway, the batting works fine.
At the pet store, farmers market or anywhere else you can find it:
3 pounds Aqua pure activated carbon.....or more commonly
activated charcoal, as in for daily cleansing pills.
Center:
Take the chicken wire and wrap it around the smaller end cap. use one of the 6" clamps to hold it on. Now clamp the 6" collar into the other side. You will end up with a 6" chicken wire tube. Wrap the quilt batting around it and put the third 6" clamp in the center. That's it for the middle of the filter.
Outside:
Now do the same with the 8" end cap and adapter. You will be left with a 8" chicken wire tube. Dont tighten the top clamp on the 8" tube. The adapter will need to come out to fill it. It's just easyer to get it to shape right if you put both ends on.
Assembly and Fill:
Take the top back off and stick the 6" tube in the 8" tube and fill the space between both sides with carbon. Put the 8" to 6" adapter back on the top and your done. If you need to pack any spaces you dont want air to go with the baged polly fill as tight as you can.
2 days, no smell. 6 more weeks to go. I'll letcha know if I have any problums.
Here is a link to the forum I pulled this from