Don, are these
commercial .22 ERMA conversion unit boxes??? They look much more refined than the pics I looked at in TBLAP...
Your thread had stuck in my mind, as my Nambu, Lahti, and even my artillery Luger long-barrel conversions just sit in a cardboard box. I currently have a slab of soft Pine on my mill and just finished inletting it for the 'artillery' Nambu barrel. Next week I'll work on adding a magazine, bolt, and cocking knob inlet. But my plan was to make it as crude as the German wartime inletted boxes.
A "Gonzo" Nambu parts box...I might even try to age it...