our reactor model has a hexagonal zirconium shell so i have to fill the region between two hexagonal prism with material ‘zirconium’，but according to the usr guide i can’t call it with ‘+hexagonal_prism1 & -hexagonal_prism2’. so what can make it works?
@flowersoul Use ~ operator
shell_region = ~hexagonal_prism1 & hexagonal_prism2
many thx ！！！！！！！！！！！！！！！！！