I've made a couple of pairs of these before, but this one is the first with stone tools only. I didn't take any photos during construction, so I hope that my explaination will suffice.
First you need to find a bent piece of wood, mountain birch being a good alternative. I chopped it down with my moose antler axe and when I got home I split it in half so that one piece has the split surface facing out of the curve, while the other has the face on the inside. Use the one with the split face on the inside.
Determine how it will sit on your face and use a flake to saw it to lenght and make the groove for your nose. Clean it up with a beaver tooth or a flake. Beaver teeth works better when hollowing out the nose room since the edge is stronger. Take your time, making such googles isn't done in a flash. Try to do as much work as possible while it's green.
Next, measure where your eyes will be and carve out the eyeroom with beaver teeth. After this is done, chances are the wood will dry out very quickly, so do as much as you can at once. The slit through should be as long as possible, to allow for the best possible sidevision. Carving the slit is easily achieved and can be done both from the inside and outside. For maximum light blocking, go as narrow as you can.
Drill one hole in each end for the string. I used a hand drill tipped with a very thin bone point. It will burn hole more than anything else, but it works. Drill from both sides and punch (carfully) through with a bone awl. Finish it up, attach a line and coat it with charcoal (not done in photo) on the inside of the eyes.