One mag that hasn't been mentioned yet that is small and pricey but usuually very narrow gauge and nicely done is Don Heimburger's Sn3 Modeler. Ferrell, Richardson and Norwood are frequent prototype info contributers. Even though the modeling articles are naturally for S-scale (I model in HO and O scales), there is always something to be learned. I have had a hard time getting it in my area and I don't subscribe to any mags because my postal service region routinely sent my mail delivered mags thru a paper shredder. But I really like the copies I do have. Besides, getting the mags from my local shop gives me an excuse to stop there more often.