This instructable is a framework for creating a concrete block cold-smoker box specifically made for masterbuilt electric smokers.
It takes its inspiration from the "mailbox mod" with the goal of being more permanent, better looking, and functional.
I did this primarily because I was having trouble keeping my amazen pellet smoker (amnps) lit. With this mod I am getting 10 hour smoke times now, so I can get a full nights sleep whilst smoking.
The instructions won't get into how to do mortar, or mix concrete, or other parts of the general construction. There are plenty of better done instructables out there for that.
All in, this setup will cost you around $100 or so not counting the cost of the smoker itself or the amnps.
Step 1: Lay the First Level
The finished picture shows a cabinet on the left. I won't go into that part. I'll just say I used a grill cart door bought for $15 on Craigslist and angle iron as the lintel to span the opening.
For the first course or level, you need to turn the center front block on its side. This will become the inside base of your cold smoker box.
This level requires (4) 8x8x6 concrete blocks and (1) 8x8x8 block. You will obviously mortar these together during final construction.
Step 2: Lay the Second Level
The second level requires (2) 8x8x16 blocks and (3) 8x8x8 half blocks. One of the blocks is turned on its side. This is very important.
If you want to be smart, a week ahead of the project you will put a 3" pvc sewer drain pipe 8" long into one of the half blocks and concrete it in.
But, if you don't have the time, you can do like I did and use whatever leftover mortar you have to pack it in after the build.
This PVC pipe will serve as the connection point for the metal ducting that acts as the chimney from the cold smoker box to the electric smoker.
Mortar these blocks in, making sure you have a good seal around the blank space and the corners. You don't want smoke escaping through the cracks.
Step 3: Lay the Top Level
The top level will consist of (4) 4x8x16 *solid* concrete blocks, (2) 8x8x16 blocks, and (1) 8x8x8 half block.
The full block that spans the cold smoker box is turned on its side. As you lay this course, you need to flip your mind upside down and think of keeping the smoke contained to the cold smoker area so it only can escape through the pvc pipe from layer 2.
Do a good job with the mortar on the inside of the smoker box to keep the smoke contained.
The second picture on this step shows the view from inside the smoker box. Notice how everything is contained.
Step 4: Add the Counter Top
For the counter top, I created a 27x26 smooth troweled remeshed concrete counter top.
You can use whatever you wish: granite, tile, etc. just make sure you consider the chimney ducting when planning the overhang.
Step 5: Add the Chimney and Door
For temporary use, I used 3" flex ducting for the chimney and a scrap piece of styrofoam with duct tape for the door.
This worked fine. The door and ducting don't get hot with the amnps.
When I finished it for real, I used painted rigid ducting and a painted 8x8 access panel from Amazon.
8"X 8" B-series Access Panel with touch latch for walls and ceilings https://www.amazon.com/dp/B00UAXGVFK/ref=cm_sw_r_awd_XjAOvbKVWN0NP
It worked great, but any door you fashion will be fine.
I had to drill (3) 3/8" holes in the door to allow air flow to keep smoke going.
I painted the door and ducting with plain old grill paint which I also used to refinish the built in grill I have next to this setup.
Step 6: Thin. Blue. Smoke.
I get about 12 hours of thin blue smoke with this setup using the amnps smoker.
The meat turns out great and I don't have to keep reloading chips.