4" Deep Shadow Moulding

Boxers from Framerica.

Framing Suppliers out of Pelham, AL also carries a line of stackable shadowbox mouldings.

AGF out of St. Louis, MO also carries stackable shadowbox moulding.

we just covered that somewhere
Southwinds also has a showcase that can be built up to about 7" deep. Glass on the sides instead of moulding so you can see all around the items. Very nice option to deep shadowboxes.
Fred @ Southwinds: 800-833-3268

Your neighborhood cabinet shop should be able to run a simple shadowbox for you for not much of a charge. Also most larger lumberyards have a mill & can run it for you. If you need a quantity of it, Foster planing mill in Los Angeles can run some more complicated profiles. Nice part about a cabinet shop is they can also give you a simple finish that is of professional quality.

Larson Juhl's 573IG, 573IB, 5731IS is a 4" moulding in gold, black & silver respectively ... makes a beautiful shadowbox. Recently boxed a bottle of wine in the balck one.