I dug through my notes and I found the measurements for the demo cell.I couldn't remember if I even had them.
The plexiglass tube was 5-1/2 inches diameter,3/8 thick.
NOTE:The tubes on average were 13-5/16 inches long,the outside tubes were different thicknesses,some were .030 inches thick and some were .043 inches thick.So that shoots any tube resonance matching theory in the bud.!!!!
A 5/16 nut was tach welded to the bottom of each inside tube
The straps on the outside tube were tack welded also and were 3/4 inch wide and @ 3-1/2 inches long
The top and bottom plexiglass plates were @ 2-1/2 inches thick.
Thats all I have,the rest you'll have to take from the pictures.
Again,from what I just gave you here and have stated before,IMHO the tubes were just random pieces thrown together,and not tuned for ANYTHING!!!!!!!!!!!!!!!!!!!!!!!!!
So take this info and do whatever you want with it,you have my opinion!
And thats all I have to say about this from here on out.I will answer no more questions about how it was built,you have what I have.
Don