What i have is a sign that has been engraved from .25 thick aluminum and i need to set a 2" aluminum return on the back of it, also the mounting system that will mount it to the wall will be 2" aluminum tubing. I NEED to find the worlds strongest aluminum to aluminum epoxy or something of the sort that will bond and hold the return on as well as the tubing which will need to be structural and hold the sign in place. The sign will weigh about 50lbs when completed. I don't want to weld the returns and tubing on due to the risk of sparking and ruining the faces brushed aluminum finish. Thank you in advance for your help!