It didn't really take but a few hours to construct it, however, I took step-by-step pics the whole way which slowed the process down. In the end I have a crossbow that will launch a bolt more than 100' feet.
Step 1: The Pieces.
Most of the components I already had on hand, such as the whiteboard, glue, screws, fork, tools etc. I went to Home Depot and Hobby Lobby for the oak strip, string, feathers and dowel. You could improvise, but I laid out a few dollars to save time and effort.
-(2) Red Oak strips 1/4"x2"x4'
-Some pieces of 1/2" thick white pine board
-Hot Glue Gun
Step 2: The Bow.
Now, since the string will be moving directly across the top of the crossbow, I didn't taper the cut symetrically. The top of the bow is horizontally straight while the bottom goes from the bottom-center to about 3/8" from the top on each end. This is to allow room to make the notches for the string.
Step 3: The Body & Stock.
Step 4: The Body & Stock Cuts.
Step 5: Assembly of Body & Stock
Step 6: Bow Attachment
Step 7: The Trigger
Step 8: Stringing the Bow
Step 9: Bolts
3/8"x12" dowels and feathers obtained at Hobby Lobby.