There are a ton of different ways to strain the stock. Place a large sieve over a large bowl and spoon the stock into it. Use the back of a wooden spoon to press onto the shells and veggies to make sure you get every bit of flavor out of them! Discard the solids afterward. Then strain the stock again through a fine-mesh sieve and that's all there is to it! You could also use cheesecloth if you prefer.