With the inbuilt booltool addon. Why i can't punch a hole. The face facing correct. Removed double verts, scale rotation are 1 and 0,. Mesh has subsurf, solidify, mirror modifier. Im using 2.9 version after boolean with brush cant find the properties canvas to remove the brush. What missing or where im going wrong. Any suggestion.
Bool Toll fail
In provided file the Bool Tool, brush type Difference, works for me.
But your screen of "helmet" object looks differently. On screen Mirror modifier has unchecked Merge, so if you used it in this condition - Bool Tool failed.
Missing Canvas menu
This menu appears only when a brush is used. Than you can see properties menu when "Canvas" object is selected. BTW you have selected "Brush" object. So when boolean operation is used also here "Brush" properties appears when selected.