Any Draftsman. But it is not cheap. Why not just make your own ?

Welcome to the Forum wickerdave!
When you say "...take the material to and have a set of build prints generated," do you mean that you want blueprints made from looking at your pictures?  If so, you'll also need to supply a lot more detailed information (dimensions, hole sizes, material type, GD&T etc) of every single part, then the overall assembly dimensions.  Downsizing by 50% is easy, if you know the original dimensions.

Cactus is right, it won't be cheap if you want it done by someone else (lots of parts to add to your blueprint for the jeep trailer). Whoever it is, they'll need access to the parts to take actual measurements.

If you just want to wing-it from the pictures, you might be able to get a student who knows computer-aided design (CAD) to do it cheaply.  Doing it this way could be more expensive and time consuming in the long run if the parts don't fit on the first try.

Tyrone

If you have a way to scan the info onto the Internet you could use a service like Freelancer.com, or Odesk.com, or Guru.com...yada yada yada.  The fees for CAD drafting typically range anywhere from $15 to $35 an hour depending on how complex your assignment is.  Some CAD operators charge by the line or page too.  If you go to one of the online sites you might find out what people are charging though.  The other option is to check in with one of the CAD groups on LinkedIn.com to discuss it with the real experts who do this every day.

But, if the sketches are huge, you might have issues getting them scanned into a web format.  You could send them in the mail once you get a contractor, but people may be hesitant to bid without a good brief on the workscope first.

As most others have said, engineer to design the trailer, shop detailer to layout the drawings so you know what to build. My engineer when asked about laying out a gate for me because the city had some boob architect do it was going to cost me $2000. I suspect a trailer would be in the same neighborhood. Then figure a steel detailer at maybe $500-1000 and you've practically bought a trailer.

Going at it yourself. Wander around a new trailer sales place and eyeball, snap pictures and write down beam sizes, crossmembers and so on and have a go at it. If you don't have adequate welding, cutting or fab equipment then, you might as well go buy one.

Just hire me.