Keep in mind there are several levels of precision when it comes to acme threads. Those used in clamps don't even state a level of accuracy per inch. Those classified as "precision' only have an accuracy of .009" per inch. Those classified as "ultra precision" have an accuracy of .0006" per inch. I would think it would be extremely difficult for a beginner to hold .0006" per inch over a 32" length, especially when the rod would have to be repositioned multiple times to complete the job. Keep in mind you'll also have to turn the areas for the bearings, turn the length for the crank handle to pass over, cut the keyways, and turn the threads for the nuts on the ends.
A complete leadscrew from H&W is less than $300.00. Most lead screws are made from 4140 or stress proof bar. The bar would cost about $50.00 plus shipping and tax and have to be hardened after machining. Just some things to think about should you decide to take on the project.