1. use a typewriter
2. use a printer. This is difficult, and risky. You might damage the original certs.
a. photo copy the cert and carefully cut the fotocopy to the exact same size as the original
b. get two more blank paper, cut down to exactly the same size as the original cert
c. using libreoffice writer, ms word, or whatever program you want, roughly guess where you need to place the name. It might be easier to adjust later if you place the text in a frame with no borders.
d. print out on one of the blanks you preped earlier
e. place the printout exactly on top the cert. With a ruler, measure exactly how many mm you have to move the text up/down, left/right. You can adjust the left/top margin of the page
f. make the correction and try on the other piece of paper
g. if all is right, try it on the photocopy
h. if this is also fine, print it on the real cert
possible causes of problems
- paper is not cut to the exact same size
- paper does not load exactly the same each time
The later might be due to the user being sloppy. Or the printer itself might be sloppy. If the paper moved only a few mm off, you might end up printing on top of the line, or overlap some other stuff on the cert.
I've done this a few times.
3. scan the whole cert into the computer as a jpg. Clean up in photoshop. Add the text you need in photoshop. Print a new cert. How well this works depends on your scanner and printer.
a typewriter will show its sentimental value sir...