Clamps work in the opposite way of the wedge, holding things together rather than separating them. They are very useful and luckily also equally easy to make.
The first task you need to do is to grind, saw or chop off appropriate lengths of the stick that are to be made into clamps.
Secondly, you should tie it off in the middle to have a point where the crack is to stop. If you take it further up than the middle it may not stand the strain, despite the string. The string on this photo is a piece of sinew.
Now, drive the wedge into one of the ends and split it up to the string.
To use it, just put whatever you want held together into the split.