Can this be troweled out? Can this be used to glue copper sheets to plywood?

Thank you for the question. The Loctite Power Grab Ultimate is not a trowel grade product and may not be well suited for the intended application described. If this is a large project you might consider using a gel contact cement designed for this purpose. Unfortunately, Loctite does not offer this type of product. Recommend you consult the metal sheet manufacturer for further assistance with your project