i cast a couple of these out of aluminum in a home made foundry. I made the pattern out of 3/8" plywood and fillete the corners with bondo. I presed the sand around it in the two peice mold box, opened it, removed the pattern then poured the Aluminum.
There is not an electric trolling motor made that could break this. I bolted a 1/2" plywood face on it so the motor would not vibrate loose.