Grays of Kilsyth...
That is an interesting request. I know of one shop that sells salmon and trout flies tied on micro tubes...smallest size tube is 1.5 mm by 10 mm. It depends on what type of trout fishing you are doing...sea run fish or...The name of the shop is Grays of Kilsyth and it is in Scotland. The owner is John Gray and he has a great website for the shop, showing lots of patterns and some of the collections that can be purchased. The theme of his flies is salmon and sea trout fishing. I use a lot of very small tube flies here in BC, and I have caught lots of sea run trout when fishing for salmon or steelhead. I haven't bothered to tie river run trout patterns on tubes yet, but I think a Golden Stone would be a fun pattern to develop. Have at look at John Gray's site... he has beautiful wee hackle wing and hair wing flies that are less than an inch long. *Had a senior moment. There is another shop that I know, Fishmadman in Denmark. They do a lot of trout flies and have developed quite a set of riffle hitch patterns for surface fishing. That site is also full of really good information, and it is owned by two of the nicest guys you could ever meet long distance. Cheers, Buff.