There is a great reference book, "The Art of the Diorama", by Ray Anderson from Fine Scale Modeler. He has many shadowbox examples, including lighting, perspective, use of Durham's Water Putty (which I love).
His "High alter of the Benedictine Abbey, Weltenburg, Germany" is beyonf words. It is a Kalmback book that was $8.00 when I got it.

Sealhead (Kansas Sunflower)