This article documents my scratchbuilding an S-scale PRR H21a quad hopper. The first one shown here has a number of errors in it and it isn't my best work. However, I have learned a lot from it, which will hopefully help with the future ones I am going to build.
Most measurements mentioned in this article are "scale", and you will be able to deduce from the context whether I am referring to actual dimensions (such as the thickness of styrene sheet used). That way if you are interested in following along in a different scale, you can easily translate the dimensions to your scale.
My reference for this project was an article in the November 1978 issue of Model Railroader titled Scratchbuild a Wartime Hopper Car by the late John R. Porter. Although the magazine article is about building an S-scale hopper, it is only of limited use since the author describes building a generic two-bay World War I hopper. I was able to use it for building the frame of the hopper car.
There are quite a few photos to the article, so I have decided to split them across several pages. Click on the section title to jump to that page, if so desired. Each page has a link to the next page near the bottom of the text.