Certificate of attendance and emailing to checked-in attendees only

[BENETNATH]

I need to provide to checked-in attendees a PDF certificate of presence with name, date and content of the workshop.
I need to email them, either this PDF certificate, or just a link to download or to generate it on the fly

Describe the solution you'd like
It would need to work on the check-in module, to add the capability to generate a certificate, with a predefined template, filled with event information, and also the ability to email only to checked-in attendees

Describe alternatives you've considered
Just having the possibility to email to checked-in attendees could be a first step, and creating a email template in this case might partially solve the problem, but the PDF is really a better outcome