If you're ever going to release a version 2.0 of this, you might want to figure out a way to stamp entire words on.
Maybe through some kind of placeholder for individual letter bits?
This will be difficult to achieve with manual stamping because of the momentum required to punch just 1 letter.
To get good results with 1 letter you need a 1kg - 1.5kg hammer.
Punching 4 or 6 letters at once would require a ~ 6kg hammer, good alignment of all the stamps and force spread out evenly on each stamp.
This is something that would require some kind of support from a machine (punching 24 words with a 6kg hammer would be tiresome/impossible for most people).