At the risk of seeming opportunistic, I'd suggest that this book might be useful:
E.N. Armoury - Shields -- " The Armoury continues with a complete book about shields. This 32-page PDF contains everything you need to optimize your shield-bearing warrior. This volume includes a brief history of shields, a collection of new shield variants (including the thrown discus shield, great shell shields, and locking shields), new shield-making materials and crafting techniques.
For the skilled shieldsman, a collection of new shield-oriented feats are presented, along with five shield-oriented prestige classes
* The Faithwarden - sworn to defend their church and faith.
* The Knight Herald - who goes forth under the banner of truce to represent the interests of his liege.
* The Ramshield Berserker - shieldgnawing fast and aggressive warriors of the Ramshield mountains.
* The Shieldmage - masters of protection and defensive magics.
* and the Tower Legionnaire - stalwart warriors and warrior-spellcasters who are masters of the tower shield.
The volume is rounded out by a pair of spells, five magic & psionic shield properties, four specific magic & psionic shields, a new alchemical item, and Belisar, the deity of shields, along with his domains of Community and Shields."