There are so many different structures on tin containers lid and bottom, like single layer lid, double layers lid based on layers, flat lid and arc lid based on lid surface, one-time forming bottom and 3 pieces body and bottom based on the bottom forming way, etc.
But normally we divide the tin box lid into two different structures: outer-rolled lid and inner-rolled lid, there is no good or bad, just a matter of taste, we can see the details from the following pictures
1. Outer-rolled lid
2. Inner-rolled lid
Also we often see 3 different bottom structures in our daily life: Buttoned bottom, covered bottom, and One-time forming bottom.
1. Buttoned bottom – there is no step in the bottom, but you can see an inner-rolled edge, the sealing effect is relatively poorer
2. Covered bottom – there is a step in the bottom and can be sealed better than the buttoned bottom.
3. One-time forming bottom.
This kind of structure forming the tin body and bottom in one time, you see no any edge or step in the bottom, it often used in small tin boxes, and the height could not be made too high: