Just to let you know the solution we are currently using is having an automated email that goes out from eventbrite post-event where the body of the email looks like a certificate that people can print/save as they wish. This works for our audience as the majority only need it as reference when they come to do appraisals as evidence of their continuing professional development.
The only slight snag is evenbrite won't allow us to mail merge the recipients name into the body of the email/certificate so we've had to do a work around which is to say 'the recipient of this email has attended...". A little shabby but we'll see how the trial goes. It's saving a lot of administration time.