Hi Mac,
Keep your eyes out for a bucket with a screw top lid. The bucket will hold your fish & etc. Cut a piece of plywood to fit just inside of the rim of the lid. Get a piece of foam rubber and cut it to the size of the wood. Now get a piece of vinyl or faux fur (or what ever else you can scrounge up). Lay the vinyl face down, place the foam rubber in the center, and place the wood on that. Now using a staple gun, attach the vinyl to the wood. Next trim the excess vinyl. Now take the lid and put it upside down on the wood. Screw the lid to the wood. Choose your screws wisely, keeping in mind that your butt will be on the pointy end of the screws.
Hope this helps,
Ron