Shell Pattern Points : Shell Pattern, Metal Casting, Foundry, Moulding Shell pattern is mostly use for drainage fittings also pipe work. This kind of pattern is generally prepared of metal and parted along center line, two sections being correctly dowelled jointly. Short bends are generally moulded and cast in pairs. Shell pattern is a hollow construction similar to shell. The external form is use as a pattern to create mould as the inside is use as a core box for make cores.