That's the inside diameter only and that will be 1/2" particleboard.
I read a series of articles years ago about someone building a studio in their home and what they did for walls worked well. They used 5 sheetes of 5/8" sheet rock (this for thos who do not know what I mean)

They made sure no seams overlapped so my concept will be similar but I'm not sure what thickness I will go with yet but I want no less than 4 and no more than 5 layers so I can stagger them like fingers with the corresponding pieces on the bottom so the top and bottom mesh together leaving no gaps. I think I will check woodworkers warehouse and cover each sheet with veneer to protect the sheetrock when opening and closing the lid and making a smoother way for the pieces to slide together.
I do not need to kill as much sound as a studio, I figure 3 1/2" added around the core of mass like this will do a good job. I'll get flight case type locking mechanisms to hold the top to the bottom and of course put it on casters for minimum floor contact.
As I build the bottom layers I am going to stagger channels for cables through the layers and put a small box on the exterior of the cab for the connections. I'm thinking at least two mic lines and maybe two speaker lines so I have a back-up speaker line. Of course once the laye is set and the cable is in that layers channel I will fill it all in with silicon.
The final outside might be tolex or some nice wood stained with the metal cabinet corners amps have and of course two handles on the sides of the top.


