Happy to answer any questions on the app, or the website. For those who are curious it has sold 61 copies in the past three days, all organically from the site. Not exactly retirement money but I'm very happy with that as a start.
Awesome work Alex! Who did all the illustrations for the book, how much did you spend on the content like diagrams?
Thanks! The content for the book came from the liquidator of a company which held the copyright. It was a complicated situation - the illustrations I believe were licensed for print to a few different publications, including magazines. A friend of mine had plans to reprint the book but allowed me to turn it into a site.