Teachers should be able to define Certificates for Download.
Students can see and print if they have fullfilled the condition for the conditional activity
It needs a unique number, it should contain data from Student user , Techer, course parameter like number of hours, date of issue, and date until it is valid.
The moodle plattform should provide a function to check the certificate ident number and display data like valid or not and a course description from the time the certificate was issued.
The design of the certificate must be free and should produce e.g. a pdf for download.
Because od the ident-number system, the Cert could be a HTML / CSS page using a bckground picture.

May be it could be solved with aölready implemented teacher functions.

In 1.9 there is a module doing this.
But I can't see any activities for a new certificate.