THE BLISTER

To make the blister, we need a mold to help us shape.

Put the aluminium sheet between the two mold and shape it.
BANG! BANG! BANG!
With the more times of hammering the sheet, We can get a beautiful blister shape.

Then use some other supports to help shaping the buckling ring sharper and nice.
After a long time hammering to get the beautiful shape, comes the important part - HAND POLISH.

Ta-da! Nice and shine!