Kainuun smithy used to be the "go to" one when lead by the Kemppainen brothers, if one wanted a Tommi puukko because they were concidered the best in Finland, they lived in Tommi puukko homeland (Karelia) and were related to the creator of the style, Kalle Keränen.
Now that Kainuun is lead by Veijo Käpylä and after that Kellam entered in business with them it seems like their quality is a bit lower, still remaining high.
Be ready to pay quite a lot of money for their work if you'll end up taking one from them.
The Tommi puukko is exclusively finnish and is deeply tied to Finalnd's history. It was created around midlle 1800 by the already said Kalle Keränen together with english metallurgist Thomas Woodward. From his friend and inspirer Kalle named the knife: Tommi.
This puukko was part of finnish fight for freedom during XIX century with Ostrobotnian puukkojunkkaris and during the Winter War agaist Russia. Yesterday, 6 december, was finnish Indipendence day, in fact. During winter war the Pokara Tommi was used as a leave gift for officers.
Its most famous and particular trademark is the blade section that finns call diamond shaped. Basically the blade has a rather slim spine while the thickest part of the blade is where the bevel start. This gives to the blade an exceptional bite keeping it light and strong at the same time. Just to give an example a diamond shaped blade 100 mm long can have a 2,5-3 mm spine, but been 5-6 mm thick in the widest point.
Silversteel used in Finland is Böhler K510 and it's probably the purest european factory steel around.
http://www.sten.fi/data/attachments/K510DE.pdf
If well forged it gets an extremely fine texture, polish up greatly, holds an edge for a really long time, it's easy sharpenung and, despite its 1,2% C content is well resilient. I've seen a 5'' Tommi batoning a 2 years seasoned 3'' olive log in one go and still shaving after a daily camp. This one was made by smith Pasi Hurttila and he's the one I would suggest if you don't want to spend a load of cash.
http://www.hurttilanpaja.suntuubi.com/?cat=10
He's a smith and certified wilderness guide. Great craftman and person.