C# Online Compiler | .NET Fiddle

using System;
using System.Collections.Generic;

public interface IComponent
{
	void Render();
}

public class Shape: IComponent
{
	public void Render()
	{
		Console.WriteLine("Render Shape");
	}
}

public class Group: IComponent
{
	private List<IComponent> components = new List<IComponent>();
	
	public void Add(IComponent component)
	{
		components.Add(component);
	}
	
	public void Render()
	{
		foreach(var component in components)
		{
			component.Render();
		}
	}
}

					
public class Program
{
	public static void Main()
	{
		var group1 = new Group();
		group1.Add(new Shape());
		group1.Add(new Shape());
		
		var group2 = new Group();
		group2.Add(new Shape());
		group2.Add(new Shape());
		
		var group = new Group();
		group.Add(group1);
		group.Add(group2);
		group.Render();
	}
}
Cached Result
printed