set/exhset/2 matches the site

public static Set Prototypical_Members()
{
    var set = new Set()
        .WithContext()
        .WithId("https://linked.art/example/set/exhset/2")
        .WithLabel("Exhibition objects");

    var paintingByManet = new HumanMadeObject()
        .WithClassifiedAs(Aat.Painting, Aat.TypeOfWork);
    paintingByManet.ProducedBy = new Production()
    {
        CarriedOutBy = [
            Ulan.Person("500010363", "Manet")
        ]
    };
    set.MembersExemplifiedBy = [paintingByManet];

    return set;
}

• 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 set = new Set
{
    Context = ["https://linked.art/ns/v1/linked-art.json"],
    Id = "https://linked.art/example/set/exhset/2",
    Label = "Exhibition objects",
    MembersExemplifiedBy =
    [
        new HumanMadeObject
        {
            ProducedBy = new Production
            {
                CarriedOutBy = [Ulan.Person("500010363", "Manet")],
            },
            ClassifiedAs =
            [
                new Type("http://vocab.getty.edu/aat/300033618", "Painting")
                {
                    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.