here is a pic of the box with the first coat of green but you can see the port right now the port is 22.5hx8wx12d I am building a block that is 22.5x4wx12 I will slide it into the port and attach it with a couple screws from the outside for daily and when I burp will pop it out and stick a little piece of putty in the screw holes until I put the block back in. When I get it built tomorrow I will take pics of it and show it in the port.
EDIT Because I know you guys will ask. I already have 6 pieces of 5/8th threaded rod I will be putting in tomorrow for extra bracing.