I have used a couple of places for stamps. This one is fairly inexpensive and stateside. Made from an epoxy type material. Great folks to deal with. Welcome to the Bunkhouse Leather
This company is outside of the country, but make good brass stamps with handle. Little pricier, but good quality. https://lwleathers.com/collections/custom-leather-stamp-leather-stamping-tools/products/leatherstamp
You may even find a member on here who can engrave one for you with a laser printer. My shop is packed up at the moment or I could. Good luck.
When I had mine made, I had 3 different sizes made so I could ensure the mark would fit on all projects.