I simply made a platform the size of the bottom of the cooler and then built a box up from there. I removed the lid from the cooler and attached it directly to the lid of the chest. The bottom of the cooler is removable to dump water or clean. The hasp, latch, and handles are from the local hardware store with a little paint and modification. The lock is a "vintage pirate lock" on Amazon that comes with functioning keys. What makes it look great is the rugged details. The pirate emblem is a belt buckle I got from Amazon also. I burnt it unevenly some with a torch, lightly spray painted it, and then curved the edges of the mock braces with a wood file, then spray polyurethane it for a vintage shine and weatherproofed it. Tip: don't try to use a large cooler, it gets heavy. Think mine is a 48 qt. Also, get a cooler with removable hinges.
Read Pirate Treasure Chest Cooler Out Of 2 Pallets by Bshizzle on 1001 Pallets!