Building a duplicating machine design ?s

I have been assigned the task of designing and building a gunstock dupllicating machine. My complaining that I just know how to "drill holes" was ignored. I'm needing some advice on how to achieve linear motion over 8ft while having the whole thing ridgid enough for the router that will be doing the cutting. I'm guessing I have to use polished shafts and somehow will have to support them all along this 8 ft not just on ends. Machine has to have a carriage with 8ft travel in x axis and machine will be about 24 in wide with 10 in of y axis movement. I am on a very tight budget and that rules out any thing elpensive like thompson shafts and bearings. Ridgid and Cheap-- thats what I'm after. The budget is less than $1000 for material. My pay is so little that my time isn't a concern for the boss. I've worked at a place building custom machines, and about a dozen other machine shops and so not without a tiny bit of skill.