So what's not practical? I've got a belt sander mounted to my desk with a device to feed bills through and then a vacuum to remove the dust. Then there's the rubber pads that push the bill against the sander just so the only spots that get sanded are the places where I stamp them. Then there's the fire extinguisher just in case the bill gets too hot. There's a big net to catch the bills as they shoot off the end of the sander and two kids to sort them out so they all face the same way. Then another kids brings them back to the desk so I can stamp them, and my wife inspects them to make sure the stamp is giving good coverage. If not, the bill gets returned to the sander to shave a little more off. Then a big magnifying glass to make sure the bills that didn't make the grade are in perfect registration so the stamps are not crooked.
I have to hide the varnich residue in case the B of C gestapo go through my garbage to see if I'm removing their precious finish.
After this, the new series bills are interleafed with the old ones so they get an even distribution when I spend them. Of course, we have to smuggle them out of the house at 3:00 am in case someone is watching. We also had to soundproof the house so no one would figure out what were doing with the belt sander running all the time, and the windows were covered to avert prying eyes.

Simple