Unfortunately i don't live in an area where birch are all that common and couldn't find any burls on other pieces of wood. This resulted in a slightly square looking cup as i had to use a straight grained piece of beech.
The end result looked nice but i had a few issues with splits along the way, and a few cracks in the finished product.
As with most things i tried to used the very simplest of tools, things that you could use in the bush to create what you need, though with this project i did cheat a little bit and used an electric sander to do some of the rough sanding.
Materials and tools:
Wood- preferably a birch burl (burls can also be found on most species of tree, olive and walnut give great results.)
Saw- to trim up the log.
Axe- for rough shaping, much quicker and easier than using a saw in my opinion.
Hook knife- for carving out the bowl of the cup.
Knife- to clean up some of the rougher shaping.
Sandpaper (electric sander)- i used grades 60, 80, 100 and 150 for sanding.
Sanding sponges- grades 180 and 240 for fine sanding.
Pan, salt and water- to boil kuksa to remove tannins from the wood.
Oil, cloth- i used olive oil as it doesn't contaminate whatever you have in the cup, unlike linseed.