I have been asked to create a design for a company for their stamps that they use to validate letters and paychecks and so on. I was wondering if anyone knew if the size i do for the design of the stamp in Photoshop would matter if i gave it to the print house to make an actual circular stamp for it!
There are different brands/standards available depending on your location. Just a random example below to give you an idea of the variety of these. What you should do is go to a local print shop and ask for a list of sizes they can produce. Then decide which shape and size works best with your design, which by the way should probably be laid out in a vector format (yes that means no Photoshop, but Illustrator or similar vector software).
Stamps can be made in any number of sizes and shapes. There's no "one size" or "one shape" for all stamps.
You need to determine the sizes available via your production house first, then decide on which of those sizes you want to use.
It is even possible to have a production house make a completely custom stamp that doesn't adhere to any predetermined size or shape. This requires a direct connection with the production provider and in this instance there would be little to no restrictions.