All instruments are made with Shellopan shells and Ayasa.
All instruments in 2018 are made from Ayasa shells.

All instruments are completely nitrided. Top and Bottom.

external 550mm, internal 530mm, high 280mm –
starting thickness before deepdrawing 1mm

Instruments are very stable you have to hit pretty hard(not recommended) if you want to de-tune the instrument. The instruments are pre-played extremely loud to check stability (only aloud by the builder, players are prohibited to do this)
Even though the instruments are stable always treat the instruments with respect.

Interesting interview by Daniel Waples with Matthieu Mark founder of Shellopan. Talking about making and material.