This looks reasonably robust: -

http://www.soundsliveshop.com/p/Warwick_RC20609A_Acoustic_Guitar_Case/WAR-RC20609A

If you want to be a real animal you could slip the internal trim out and put some flat sheet steel (keep it thin or it will be stupid heavy) around the soundbox end and pop rivet it from the outside - keeping the rivets close to or even in the edging strip.