On Friday we made rock tools in class. First we learned the bipolar technique - basically you put a small (relatively) rock on a big rock (the anvil) and hit it on the other end with another big rock (the hammer). Hopefully large pieces with sharp edges will split off. Small pieces with sharp edges are also useful - though not as convenient to hold on to.
After making a bunch of stone tools (the sharp rock fragments) we were instructed to gather a segment of vine maple for a knife handle using only our stone tools to cut it to appropriate size. After an hour or two of working at it I finally got one end of the handle cut down appropriately and have made it part way through evening out the other end. It is quite arduous and definitely has given me much more appreciation for steel tools.
The next rockworking technique we learned was percussion flaking. Basically you take a hammer rock and hit it downward against the edge of the rock you are trying to shape, and if all is successful a largish flake will come off the bottom from where you hit it. To make an edge you can alternate sides you are flaking off - after you get your first flake turn the rock over and strike near the edge of that flake to knock a flake off the other side. Repeat around the rock as desired. After fleshing out the edge you can repeat the process on the larger protrusions to sharpen it up. Apparently thin, smooth looking rocks and/or rocks with fine grain are desirable for use as the stone being shaped. (Oh and you can use the flakes that come off as little tools as well.) Most of the rocks we were trying with (and had collected ourselves before we knew too much about what we were looking for) were not particularly desirable for use in tool making.
Between banging my fingers between rocks, holding rocks while banging them, and sawing at wood with little sharp rocks my hands took more damage that day than they have in a long time (including the abuse I give them while practicing handdrill). But it was still fun to make tools with such readily available material.