Few months ago a friend of mine told me he wanted to build his own and I was immediatly hooked again. So by now the complete crossbow is finished; the stock and mechanism are beech from hardware store, overall length about 3 feet, 40 mm at widest point; leaf spring, bolt clip and guide block are ash, spring and clip were bent with steam; prod is oak (Quercus Robur) 34''ntn, 100# at 12'' draw, 42 mm at widest point, double nocks for bastard string. String, stirrup and bridle are store bought hemp, I made the stirrup just like completely served endless loop bowstring but I plan to put an iron one someday or wippe ring.
The mechanism is a hybrid of roller nut and claplock, after the nut is released it moves forward until the string hits the slanted notch and rolls out. This way pressure is applied behind the axle and hopefully less strong material is needed. I live in an apartment now so everything was done with hand tools, not that much of a problem since stock wood was cut in square blanks. I had to glue two pieces to gain extra depth though, and will try to find real wood in the future and to lay it out to my true heart's content.
And there it is. Sorry about picture quality. Any comments and questions are welcome. Also I would like to ask if there is a method of matching bolts to prods. It's nice not to have to worry about spine but are there recommended bolt weights for different strength prods? In primitive archery it is now an unofficial standard to shoot 10 grains of arrow weight per bow pound yet I have a feeling 1000 grain bolt would be a bit too much for a 100# prod