Does anyone have any experience doing this? What size live traps are best for this purpose? Any tips or techniques that anyone has had success with would be much appreciated.
Thanks CF

5x5x24 or similar size cage set on a running pole with beaver for bait. Cover the top to keep birds from seeing in.

That looks so cool I want to do it.

Awesome, pretty much the same way I do it with a 120 and a box. One more question, what is the purpose of elevating the cage? Thanks!

Makes them come in from the front of the trap and not the sides

Pine Marten, (Martes martes) is a European specie. It does not exist in North America. That is (Martes americana), the American Marten, a totally separate specie.
There are eight species of marten , world wide.

That said, marten are easily caught in cage traps, the 8 X 8 X 24 inch size, being the best choice.I
If you're wanting them in good shape, the trap should be fastened to a small square (wooden) box at the back of the trap, allowing the captured marten to 'hide'.
Marten are highly stressed and injury and death can occur in even cage traps, so the nest box attachment offers refuge and keeps the marten calm until the trapper returns.
I spent time in Idaho with a trapper who would capture female marten this way, put them in captivity, after the young were born, then weaned, he would remove the female.
He would return the female marten back into the wild in their territory from which they came.
Beaver meat and skunk essence was the bait of choice, as I recall, yet marten can be caught on a number of baits, including strawberry jelly.

I use cage traps almost exclusively even when I'm not required to by law.

I like a trap not bigger than 6x6x24. The reason I like small traps is that it is easier to get the marten out of the trap to check it's sex. If you want them alive and healthy it is very important to keep them absolutely dry.

I'll attach a video showing how I release them.

Notice the great color of the female marten I release; great genetics to have out making more beautiful marten.
I didn't trap that line this year, but last season I caught a marten that made the actual top lot. A lot of 20 skins out of 60,000. These little females are at best only worth half of what a male is worth, so I think it makes much more sense to leave them as breeders.