object/bust/1 matches the site

public static HumanMadeObject Bust_1_Technique()
{
    var bust = new HumanMadeObject()
        .WithContext()
        .WithId("https://linked.art/example/object/bust/1")
        .WithLabel("Bust of a Man")
        .WithClassifiedAs(Aat.Sculpture, Aat.TypeOfWork);

    bust.ProducedBy = new Production()
        {
            Technique = [Aat.Term("300264383", "Sculpting")],
            CarriedOutBy = [
                Ulan.Person("500015886", "Francis Harwood")]
        };

    return bust;
}

• Metatype classification The second argument classifies the first, not the object: WithClassifiedAs(Aat.Description, Aat.Statement) says this is a Description, and Description is a kind of Statement. The Plain C# form shows the nesting.
• Terms outside the registry The vocabulary registry holds only the terms linked.art itself publishes, so a dataset's own concepts, places and people are written with Aat.Term, Tgn.Place and Ulan.Person, giving the id and the label.

var humanMadeObject = new HumanMadeObject
{
    Context = ["https://linked.art/ns/v1/linked-art.json"],
    Id = "https://linked.art/example/object/bust/1",
    Label = "Bust of a Man",
    ProducedBy = new Production
    {
        CarriedOutBy = [Ulan.Person("500015886", "Francis Harwood")],
        Technique = [Aat.Term("300264383", "Sculpting")],
    },
    ClassifiedAs =
    [
        new Type("http://vocab.getty.edu/aat/300047090", "Sculpture")
        {
            ClassifiedAs = [Aat.TypeOfWork],
        },
    ],
};

Generated from the object the example builds: every property that is set, as object initialisers, with the vocabulary constants where a term is in the registry. The fluent helpers are a convenience, not a requirement; this form and the one as written produce the same JSON.