This might not help much but I have to say this, when we all started building guns we were all confronted with the same problem. What I did was to start a library. Some books are better than others for showing detail. The sad thing obout original work is that most are so badly work you can't really tell much. One book that helped me was Contempory Makers of Muzzleloading Arms by Robert Weil.It has some good closeups of the various carvings. It got me started. But nothing beats a closeup personal hands on examination.When I went to Shows I took pictures, lots of close up macro pictures. Over time you will be discrimate as to what is good and what is ,well not so good. If you need a list of some other books, respond and I'll post alot of others. The parts suppliers have a good selection of them. Also some of the makers have web sites, with examples of their work which is also a start. Rocco art is all over. Its in stone carvings, printed paper money, even wallpaper designs. Hoped this helped some. ....Georege F.