Aluminum Devcon and Marine Tex work great. One good thing about Marine Tex is if mixed according to the instructions, the viscosity is thick enough so it tends to stay in place.
You can buy Marine Tex at Lowe’s, Home Depot, and many hardware stores.
JB Weld will make a strong bed, but it’s viscosity when mixed tends to be a little on the thin side, making it more difficult to work with.