Are you talking about changing from steel floor to wood floor? (wood bed conversion) If so, there are a lot of metal parts needed besides the wood boards. As to making your own boards, many people choose to cut their own boards for a variety of reasons. It can be done if you have the tools and skill. We prefer the dimensions in our instruction,
http://www.mar-k.com/bedwood_dimensions.pdf , in which you make the measurements on your own truck and cut the wood to fit. If you follow the instructions, your wood will fit correctly. Be sure to use a good exterior finish. Take the time to do it right and you will not be disappointed.
Mar-Ktech