I have created a Section that can be put into any sectioned theme on Shopify. It works by making a Clickable Image and places all items chosen either in the cart, or in the checkout.
The Section gives the option to add to cart, or straight to checkout with optional discount code auto applied. You can also combine this with Shopify scripts if you are a PLUS Merchant. By Default you can use up to 10 products in this, but very easy to customize to add more.