Construction: They where made by solid piece of wood and not plywood. Solid wood requires the use of several planks to make up a shield board. It could take 7-9 planks to make one board. The planks were 3″-9″ wide. There is no evidence how the planks were held together. The rarity of long grips, edge bindings, and the absence of suitable iron clamps or nails in shield burials, leads researchers to believe that they used glue, dowels, ledges, a leather rim or cover. They were able to make wood curve by the use of steam to soften the wood.
Decoration: The use of decoration was probably not just for display, it could have served a purpose of identification in battle. They could have painted the front of the shields but its hard for archeologist to prove that in there findings but there are written accounts of shields being colored.
(Dickinson pg.50)
Anglo-Saxon Shields 