The project started with a "street find" of a discarded Wally*World gas grill, with a 22.5" diameter lid.  Instructables gave the plans for basic UDS but this project added a very functional and convenient air control plus cold smoking capabilities. Later on, I added a rotisserie.

The vertical black pipe provides the temp control (air control) and the silver tube on the left is the cold smoke source which adds tremendous versatility and control. The yellow box is a jump-start battery that runs the air pump which gets the cold smoker started and after it has run for a few minutes, nature does the rest. It was a fun project that produces outstanding temperature and smoke control - not to mention the food.

Added Notes, I have added some pictures because of the expressed interest.  The external cold smoker instructions can also be found within Instructables pages. The cold smoker aluminum tube simply has a round piece of expanded metal sheet in the bottom of it to keep the wood chips or chunks off of the chain link fence post cap. If there is interest, I will also add the detail for this device as the damper system works very well and is cheep, as is the author.  It makes cold smoke from scrap wood, chips, sawdust, pellets, twigs, etc.. This expands the UDS to be able to smoke fish, cheese, bacon and anything that should not be exposed to heat while smoking. It can also be used to add smoke while BBQing if more is desired.

I also added a removable battery powered rotisserie unit to this UDS and as a result, it has made for an extremely versatile cooker / smoker. The rotisserie was fabricated from a discarded charcoal kettle drum (I saved it from the dump because of a rusted  bottom).  The rim size (22.5") allowed it to fit snugly into the top of the UDS barrel.  I used 14" long steel wires (coat hanger) to hang the UDS's charcoal basket from the original internal UDS grill supports (1" long eye bolts). I then cut the bottom of the discarded kettle grill out to match the diameter of the basket. The bottom of the discarded kettle rested about 2.5" above the top of the UDS. This allowed me to mount the rotisserie supports to the drum without having to cut unwanted slots in my drum.  I cut two slots, to accommodate the spit, in the top of the discarded kettle's bottom that allows for the rotisserie spit to pass through.  When attaching the rotisserie, I simply align the slots with the UDS permanently mounted side brackets.The alignment is a snap and the entire mounting process takes less than a minute.  A simple video of the rotisserie in action can be viewed here: http://www.newyorkshopexchange.com/video/865/video-business-guide/woodkrafter