Free Certificates of Completion
There are several websites that offer free certificates of any kind that you could easily find on search engines like Google and Yahoo. These offer certificate of completion templates as well as countless others that you may come to need in the future. Simply download the certificate of completion file, print out as many certificates as you need (preferably on a color printer) and sign away. If you do not want to write in the names by hand, you can open the files in Photoshop or Paint and use the text tool to type in the name of the recepient and even use a script font for the signature.
Another way to go about this is if you have a copy of Microsoft Publisher, Microsoft Word or another publishing tool. These have templates installed right onto them. Even if they do not have the exact certificate you are looking for, they are easily customizable and you can simply change a few things to get it the way you want it. Again, you can type in the name using the publishing tool or simply print it out and write it by hand. You can even find or create your own stamp or emblem to put on the certificate to make it look more official.
These are best done when using a color printer as the colors are more lively and celebratory than if you use a black and white printer.