This shows a key part of the structure
of the bottom inside. The triangle aft is taped in along with
the bottom of the case. It has a bed of uni under it as well.
Three layers of 750gram tri ax on each side. plus a layer of
450 DB over the lot.
The top isn't quite as heavy duty but still
I didn't skimp on material.
I used stringers for shelving, as you do.
The leading edge of the board should be
positioned about 180mm back from the main beam.