I've been in the process of making one for a while. A combo unit that can be used as a charcoal grill or a wood burning grill or a smoker. It's on hold while I get some paying jobs out the door. Can be made simpler than what I have done. Although this one should last a long time, the body has 1/4" wall.
Here's a pic from several weeks back. It is now sporting legs, wheels and a chimney. One day I will finish it....
You can take the man out of the woods but you can't take the woods out of the man.
"Celebrate your harvest with a Bloodtrail Ale(tm)!!"
"It CAN Be Done!"
Here's a pic of my COLD smoker. I do salmon sides.
The fire box is a 5 gallon steel bucket on the ground and the smoke chimney is a flexible dryer hose. This leads to the wooden box with screened trays.
Since you do NOT want the temperature of the fish to exceed 26'C (80'F), the heat and vents need to be monitored. I use an alarmed thermometer.
Smoke all day with maple wood and you've got cold smoked salmon that melts in your mouth. MMMMMMMmmmmmm.