We created our own on a former boat, basically we 'framed/formed' it with foam panels, then sealed it with a few layers of epoxy resin and cloth (used regular construction styrofoam, OK with epoxy but would dissolve with polyester resin).
For the lid we made a two part lift lid (top load) and put the same foam w/epoxy skin on the underside. A small opening section for quickly grabbing a beer, but both lids up to load/rearrange things.
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)