I bought a Camel Back bridge kit from Garden Texture
First of all, let me say the kit is absolutely wonderful. The quality of the lumber is outstanding and the directions are great as well. If you want to cut your own lumber you can buy the plans wich are basically a full size template to build on. (I did order just the plans for the trestle I want to build, as I did not see a kit that met my needs. I did buy ready cut lumber pallets, however, and the wood is just so well cut!) Everything is cut to length, including all of the angles. You do have to bend the arch and laminate four pieces of redwood together.
I ended up buying some extra clamps.