Yes, this reply is over a year after the last reply, but I just wanted to add clarity based on what I remember when speaking with others on this topic, and also speaking with Mr. Milholland in person. The following applies to those of us who downloaded the PDF plans. The WEB-## is not the serial number. Otherwise, many of us would have the same serial number. The actual serial number can be found on the email you received which contains the link to download the plans. On this email, you will see the order number next to the date that it was ordered. It will look like this: [Order #123] (January 1, 1900). The serial number is the order number. Using this example, the serial number would be 123. I've attached a copy of what I received but altered to match the example above.