Step one was pulling out the sink, cutting a piece of plywood to fit, and glassing the hole flush. I used layers of woven fiberglass and Gougeon Brothers West Systems Marine Epoxy to fill that gap, along with another hole in the right back corner. I sanded the bottom of the hood heavily, and then began painting in the same epoxy, pigmented black, to completely cover the fiberglass bottom. This will create a durable, easy to clean and repair surface for the light acid preparation, resin mixing, and fumed silica work that will take place in the hood. Our welding shop is fabricating a base to support the hood and surround the acid cabinet that will be placed below.
I'll post more pictures when the project is finished and installed.