I would a html form and script created that will 'automatically' create PDF documents based on variable form data and email them to the user.
The user enter their name, email address and other input data into the form by selecting various options from multiple choice form fields.
When the form is processed the user is emailed a pdf document / certificate.
webmaster is also emailed a copy each time.
The idea is that users create their own variable certificates. I have uploaded a certificate border for the background of the pdf to this project description.
Should be simple job for any programmer that knows what they're doing.
Any questions please ask me.