class FooRepo
{
    public string ConnectionStringName { get; }
    public string SchemaName { get; }
    public string TableName { get; }
    public Dictionary<string, int> ColumnLengths { get; }
    public Dictionary<Type, SqlDbType> TypeMappings { get; }

    // some queries...
    public IEnumerable<string> GetStrings(object param1) { ... }
}

class Foo
{
    public Foo() {}

    public string Bar { get; private set; }

    public string Qux { get; }

    public class Builder
    {
        private Foo _foo = new Foo();
        private Builder() {}

        public static Builder Create()
        {
            return new Builder();
        }

        public Builder Bar(string bar)
        {
            _foo.Bar = bar;
            return this;
        }

        public Foo ToFoo()
        {
            return new Foo()
            {
                Bar = _foo.Bar
            };
        }
    }
}

var foo = Foo.Builder.Create().Bar("baz").ToFoo();
var bar = foo.Bar;

var foo = new FooRepo(string connectionStringName, other parameters...);
var bar = remute.With(foo, x => x.ConnectionStringName, "updated connection");