Just in case this hasn't been thought of before.
I'm using old beehive boxes as a cold smoker.
These seem ideally suited to smoking. For those not familiar with beehives each 'section' (usually called a brood chamber or a super) is essentially just a hollow stackable rectangular box with rebates on the inside where the 'frames' (which support the honeycomb are hung).
It is then just a simple matter of stacking them on top of your cold smoke generator, adding horizontal supports by placing them on the rebates, and hanging meat as required.
Now buying prime cedar boxes (or even 'cheap' pine ones) just for this is going to be pricey, but occasionally beekeepers have to discard boxes because they have become rotten in places, or have become too damaged by use/vermin/woodpeckers/bears(!) for economical repair.
The nice thing about recycling these boxes is that because they've previously been used for food production you know that there aren't any nasty chemicals lurking around.
If you know any beekeepers/clubs you could put out some feelers. If you get them from this source then ask for any old/broken frames too as the top bar has already been cut to fit.
Just one warning - not all beehives have the same 'footprint' so if adding boxes from different sources do check out that they'll stack .
I've got some bacon smoking in an old hive now so maybe some pictures later.
Philip