304 vs 316 Stainless Steel for Outdoor Sculpture
The grade decision costs little at the quotation stage and a great deal once a piece starts pitting. Here is how to make it properly.

Two completely different routes to a large sculpture, each with a form language it suits and one it fights.
This is not a cheap option and an expensive option. Sheet metal fabrication and mould made laminate produce different kinds of object, and the form you want usually decides the material before the budget does.
Faceted, geometric and continuous curved forms. A mirror polished stainless animal reads as a modern interpretation rather than a likeness, and it will stand outdoors untouched for decades. What sheet metal cannot do economically is soft modelled detail: fur, facial expression, cartoon proportion.
Exactly what metal cannot. A master form is modelled by hand or digitally, a mould is taken, and the laminate reproduces every piece of sculpted detail. It also takes any colour, which matters for character and brand work where a specific palette is required.
A large fiberglass figure is light enough to place on an interior floor, a roof terrace or a mall atrium without structural checks, and light enough to move with a small team. The equivalent in cast metal may need a structural report and lifting plant. On an upper floor, this often decides the material on its own.
Stainless steel outdoors is essentially permanent with washing. Fiberglass outdoors depends entirely on the topcoat: with a UV stable system specified at the quoting stage it performs well for years, and chips touched in early stop moisture reaching the laminate. Specified as an interior coating and then left in full sun, it will chalk.
A fiberglass mould is a real cost that is paid once. The first piece carries it and every subsequent piece is far cheaper. Sheet metal fabrication costs roughly the same for the second piece as the first. One figure tends to favour metal. Six identical figures strongly favour a mould.
If the form is geometric, permanent and outdoors, fabricate it in stainless steel. If it is modelled, coloured, repeated or going on a floor that cares about weight, mould it in fiberglass.

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View detailsIt can be coated to a convincing metallic finish, which is common for large decorative figures. Close up, and over years outdoors, it is a coating rather than solid metal and behaves like one.
Long enough for a production run of identical pieces. If repeats are likely, say so at the start so the mould is built for that rather than for a single pull.

The grade decision costs little at the quotation stage and a great deal once a piece starts pitting. Here is how to make it properly.

A flawless mirror finish is decided during welding and grinding, long before anyone reaches for a polishing mop.

What weathering steel does over its first years outdoors, what it does to the paving underneath, and what to detail at design stage.
Send the position and the constraints and we will tell you which way the decision should go for your case rather than in general.