Birch bark is a lovely material that can be woven, folded, and lashed into a great variety of projects. If done mindfully, birch bark can be sustainably harvested without permanently damaging trees.
The images in this Instructable were taken by Alex Kamerling at Week in the Woods: http://weekinthewoods.org/
Step 1: Tools
Bark may be harvested without any tools, but it is nice to have a short sharp knife, ladder, string, ruler, straight edge, soft wax, and scissors.