Study.EU propuso este tema para que otra persona hablara de él.Generating PDFs
...and using them as mail attachments.
wkhtmltopdf seems to rely on an outdated engine, Puppeteer is resource-heavy, and (update) this new gem seems useful but is not yet production-ready for Heroku: https://github.com/igorkasyanchuk/rails_pdf
What approaches exist, which are good in practice?