For those interested in taking only the most minimalist approach to DIY projects, check out this bushcraft wooden comb.
It's carved from a sliver of hardwood using only a pocket knife and a steady hand.
Of course, this sort of project asks the question, "if you're in a situation where you only have a pocket knife, would you really even need a comb?" But, of course, that's not the point, is it?
Get the full how-to at Jon's Bushcraft: Carving a Bushcraft Comb