As Ian says, one panel (of most models in 1455 series) slides out.
I inserted an aluminum panel in inner guide slots and mounted my PCB on to this panel.





Have a look at the photo table of the 1455 series pages on the Hammond site. The selection guides are conveniently and well organized.

https://www.hammfg.com/electronics/small-case/extruded/1455.pdf

https://www.hammfg.com/electronics/small-case/extruded/1455/photos

 

If you have a 3-D printer you can do wonders printing cover plates and end plates for extruded aluminum.

A 3-D printer starts at under $200.
You will spend a lot more than $200 for customized cases.

 

As Ian says, one panel (of most models in 1455 series) slides out.
I inserted an aluminum panel in inner guide slots and mounted my PCB on to this panel.

Gotcha so you added a piece of metal in one of the middle slots then mounted the board. I don't think that will work i kinda think I need something that can close vertically. I am using really different buttons and switches. I think your probably right about a 3d printer for the prototype.