tin can, container, jar radical (no. 121)
缶 centers on a container, especially a metal one: a tin can or jar. The radical sense is the same container shape used as a component in other characters.
缶 is a pictograph of a lidded container or jar. The modern form preserves the basic shape of a vessel with a top and a hollow body.
The top horizontal stroke is the lid, the short vertical strokes are the rim, and the lower boxy shape is the body of a tin can or jar. Picture a sealed metal container: 缶.
For カン, imagine a tin can: can -> カン. The English word 'can' sounds exactly like the reading, and the kanji itself is a can.
can; tin
canned food; tinned food
kettle
drum (e.g. oil, gasoline); metal barrel
empty can
tinned tuna; canned tuna
can opener
eighteen litre drum
aluminium can; aluminum can
canned crab
jerrycan
steel can
spray can; aerosol can
beer can
tin can
paint can
large can with a handle; pail
aluminium can shaped like a bottle (aluminum); metal bottle
500 ml can
cylindrical boiler