Disappointed by the news that the Trump administration was walking back the plan to put Harriet Tubman on the $20 bill, I created this stamp to convert Jacksons into Tubmans myself.
Although anti-counterfeiting laws prohibit the willful destruction of, and stamping of advertisements upon, paper money, pursuant to I.I.18 U.S.C. § 333 of the United States Code, stamped currency is fit for circulation so long as its denomination remains legible.
A full explanation of the legality of currency stamping can be found here:
Handle is 3D printed, stamp is laser engraved.
More info at tubmanstamp.com/