I have read all the information about designing a Xbow and prod. Its all very interesting as an overview but I am not an engineer and I couldn't work out how to use the information to come up with a plan for a prod. I gave it all to an engineer friend and he came to the same conclusion.
What I want to do is make the Xbow shown in the design plans with a steel prod of about 150lb draw weight so I want the dimensions, in particular the thickness of the steel. That dimension is not shown on the plans you provided.
Can anyone help or am I supposed to do complex calculations. If so I will need an engineer as that part of it way beyond me.