If you want a good, simple pattern for an authentic-looking chest, you can't beat this one by John Lambert. Unfortunately, it's on the small side. If you have long and bulky stuff like armor or swords to carry, you want something bigger.
But, 20" wide planks are prohibitively expensive, and to use smaller boards would involve a lot of complicated joinery. So, here is a pattern for a four-foot-long chest that I drew up. As with the chair, bed, and table patterns, I took it as a challenge to make the most of a single sheet of plywood.
OK, it's not particularly authentic, but it's prettier than a big blue plastic tub, which is what I used to haul my armor around in. (The tub had wheels, though, which was very nice!) Stain it dark and nobody will give it a second look.
For this chest, I bought 44" leather belts with pewter-colored buckles, and used carpenter's glue and decorative upholstery nails to attach it to the chest. The belts serve as hinges, hasps, and decoration, all at once. At Wal-Mart prices, the belts were cheaper than buying wrought-iron-looking hardware, and saved weight as well.