Well, I've covered all the main Barry classes in varying levels of detail as my fancy and my sources permit. The other absorbed lines won't be nearly as simple - the Barry Railway was founded late and had a particularly organised and disciplined locomotive policy. There are some obvious books on the Barry Railway locomotives for those who wish to learn more. My main references have been "The Barry Railway Diagrams and photographs of Locomotives Coaches and Wagons" by Eric R Mountford, Oakwood Press 1987, ISBN 0 83561 355 9, Russell's "A Pictorial Record of Great Western Absorbed Engines", Oxford Publishing Co, 1978, and RCTS Part 10 - Absorbed Engines 1922-1947, 1966. I haven't been able to justify to my self purchasing the Welsh Railway Circle's Barry Railway Drawings, but its companion volume Rhymney Railway Drawings is an excellent publication, and I imagine this one is just as good and much more readily available than the older volumes. The drawings are to a larger scale too which is always a good thing.
There are also on line sources for photographs, almost too many to mention, search engines being your friend, but this flickr collection by Nick Baxter and the 813 fund's collections deserve a plug.
For those who haven't tried the exercise of interpreting drawings and photographs, this page covers how I go about it. The sketches are strictly representative. Unless you have a full works general arrangement drawing its difficult to have much confidence about a inch or sometimes three here and there - weights diagrams aren't nearly as accurate as one might hope - and the minefield of locomotive condition against date, not to mention the problems of understanding what you are looking at, means nothing is truly set in stone. In general when I haven't understood something I've omitted it. Pipework and inside valve gear especially. In answer to the always vexed question of liveries, drawing out lining is a royal pain in the neck and doesn't in my opinion add very much to the legibility of the sketches, so I don't do it! I've given rudimentary colours to the sketches because it looks prettier than grayscale, and the contrast between the pre group and GWR green helps make it obvious which is which.
Edited by JimC