LargeObjectBeginning.cs

public class LargeObject : IDisposable
{
    private static readonly Cleaner<LargeObject, NativeState> _cleaner;

    static LargeObject()
    {
        _cleaner = new Cleaner<LargeObject, NativeState>(Cleanup, OnError);
    }

    private NativeState _state;
    // Plus some heavy stuff that we don't want to keep around once the object is no more referenced

    public LargeObject()
    {
        _state = new NativeState()
        {
            _handle1 = (IntPtr) (DateTime.Now.Ticks),
            _handle2 = (IntPtr) (DateTime.Now.Ticks + 1),
        };

        _cleaner.Track(this, _state);
    }