I am having fun engraving old patent drawings on tile. Finding them is always a challenge because there are some sites that have fake drawings and of course are not public domain. Other sites have taken the originals, colorize the drawings and add extra information. So what is a maker to do?
I came across this site that has all the information and links you need to find legitimate drawings for use.
Have fun!
https://www.upcounsel.com/old-patents
This site has some great drawings for inspiration. They want you to buy from them. Search the USPO for the ones you like.
https://vintageinternetpatents.com/first.html
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