Kool Tack now offers Aluminum Composite Sheeting (ACS, similar to ePanel, DiBond, AlucoBond) with an excellent dry mounting adhesive. I tested 2 mm thickness, but I guess the adhesive could be applied to any standard ACS. It may be ordered from Kool Tack distributors custom-cut to any size, with smooth-finished edges.
Aluminum Composite Sheeting is better than plain aluminum sheeting because it is more rigid and durable, and one or both sides may be finished. Thin aluminum could be accidentally bent in handling quite easily, but 2 mm ACS is very difficult to bend by hand.
Mounting to ACS has some unique benefits. The surface is very hard and smooth, so orange peel is literally non-existent, especially if you use a Perma-Lon Release Board. The back of the ACS is finished aluminum, so it looks great if it is to be on an easel, leaned against a wall, or otherwise displayed unframed. The adhesive on this new Kool Tack product is good for the long term, but it is actually reusable, so it is perfect for temporary mounting/display of large digital graphics. You can dry mount a heavy-paper digital image to it, remove the photo, and then mount to the board again, repeatedly -- the adhesive stays on the board. As a consultant during its development, I used this Kool Tack product up to 20 mountings, and it still holds securely. It really is amazing.