Wyvern has covered it pretty well. Only thing I have to add is, if you decide to do a wood prod, make it's lengthat least 2 1/2 times the draw length from nock to nock. 3X would be even better. The one I made was only twice the draw length and it didn't last long. A backing of some sort, like rawhide, will help one hold together better. A backing of sinew will not only hold it together but really ramp up the draw weight and performance.
But for that muchcost, a good steel prod from alchem would be far preferable. You can't keep a wooden prod crossbow bent, or even strung, for hours at a time or it will take a set and performance will go straight in the dumper.
Here's a closeup of the fletching on my bolts. I notice that Wyvern has gone an extra step and put nocks on his. Obviously, I haven't. Instead, I fletched mine so the string will run cross grain so the string would have a hard time splitting them. They fit right in with my cheapskate reputation too. I belong to an all traditional archery club and many of the guys shoot wood arrows. I pick up broken cedar arrows and turn them into crossbow bolts. Free ammo!
I do take some ribbing from the guys at the club but, all in all, they think my old timey crossbows are pretty cool.
I have not chrono'd my crossbows, butthe125 lb steel prodseems to zip these cedars downrange pretty quick while the wooden one was noticeably more sluggish. The bolts tipped with blunts do a number on small game, but I'd want to use a heavier wood, like hickory, maple or ash, for hunting larger stuff like deer and elk.
I'd like to make another crossbow this spring, with a stouter prod and using bow irons instead of bindings. I saw a crossbow recovered from a wreck of a Spanish galleon off the coast of Corpus Christi that I'd like to replicate.