This is how to make a smoker oven. You can smoke fish in it.
First you have to make the outer shell of your oven. You have cut it from 2 mm metal sheet and then bend it with a press brake. Next step is to make the smoking chamber. You weld it from metal sheets and then make holders for the grates. You weld the holders to inner sides of the smoking chamber. After its done you can weld it straight to the outer shell. Under the smoking chamber is the fire chamber. You have to bend it from a metal sheet with a press brake.
Next step is to make a drip tray that goes under the grates. You cut a sheet that is 1 mm stainless steel. Then you bend the corners up and weld the shut.
The doors for smoking- and firechamber you make from 2 mm metal sheets. First you bend them with a press brake and then weld the corners shut. Then you have to drill holes to center of the doors so you can place handles with bolts to them. You need to turn hinges for the doors. Then you weld the hinges to sides of the chambers so you can attach the doors. Under the doors is a ash pan.
When the oven is assembled, treat the surfaces with thinner so you have a clean oven to paint. You can paint it with heat-resistant spray paint.