12 years ago I built a keezer from a freezer by putting the wood band around the perimeter like others. But that is where I deviated.
I installed a 4" PVC pipe with a 2" PVC concentric pipe inside it. At the keezer, I had a 4x2 concentric adapter that blew air down the 2" pipe (Dayton blower). At the business end, I had a 4" toilet flange with the tower on top of the counter. The 2" pipe stopped about 2-3" from the flange. The beer lines ran down the 2" pipe.
The cold air from keezer blew down the 2" pipe shilling the beer lines the whole way. At the end, the air turned 180 degrees and ran back to the keezer via the annulus of the concentric pipes.
Worked very well. Sold that house and it conveyed.
Was going to to post pictures but appears no option to do so.