We hang alot of ACM panels (building numbers and such) with some home made stud cleats. We stud weld aluminum studs onto .040 aluminum cleats, mostly 2" wide and 4" tall. Apply a couple strips of VHB tape to back of cleat. You can then apply that cleat to the back of an ACM panel. That stud will help hang the panel on the wall until your adhesive sets up. PowerGrab Ultimate works pretty well for holding up panels and keep them from moving. Scuff up the back of the ACM to make sure you get a good bond.
