Those acrylic backing plates are going to crack at some point. The author should look into aluminum composite panel (Dibond is one brand name). It's a sheet of

Those acrylic backing plates are going to crack at some point. The author should look into aluminum composite panel (Dibond is one brand name). It's a sheet of HDPE plastic sandwiched between two thin layers of aluminum, and is much stiffer and stronger than acrylic of the same thickness.