Hi Chambers
I couldn't find a pic of the smoker I use although it's a similar idea to the one below
(mine is a much more basic design). I've heard of people using ammo boxes and various other setups to build their own
(I do have an old 303 ammo box in the attic but think I'd rather leave it as is...)
You can also use some barbecues with lids in a similar fashion.
You can buy flavoured smoke chips to scatter in the smoker or just make your own
(choose carefully 'cos some woods can be nasty/dangerous/potentially fatal). Definitely don't use painted or treated woods
(I know one person that did this and is lucky to be alive)
Some folk advocate soaking the fish in brine solution before smoking but you can smoke them without.
I like mine with chorizo in the cavity and any edible herbs I can find (or buy ahead of time)
For a smallish trout
(less than a lb or so) It'll be smoked in 15 minutes or so. Sitting beside it can be the longest 15 minutes of your life as the aroma is incredible. You can also use them for smoking gammon steaks and a whole host of other foods.