Check out these pictures from Metalbond reader Mike of a confinement box built by Redneck Mark:
Redneck Mark (who goes by Bootsncamo on Recon) also built my cage.
I notice you have been featuring some confinement boxes on your site. Here is the one Redneck Mark made for me. The large flange on the bottom of the door is for an electromagnet lock. It also can be locked both from the inside and outside with a padlock.
Thank for the pics and info, Mike!