So the premise of the problem is the need to egress traffic to the internet from a private VPC, without using an expensive NAT gateway. The solution is to do NA

So the premise of the problem is the need to egress traffic to the internet from a private VPC, without using an expensive NAT gateway. The solution is to do NAT manually by having an EC2 instance in a public VPC, and tunneling traffic from the private VPC through that instance. The meat of the article is how to create that tunnel using S3 for data transfer instead of using a more traditional VPN service.