The title says it all.
Well, first they tell the patches how cool it is to smoke…
Then they send them somewhere like here Island County Jail, WA Inmate Roster Locator, Visitations, Sheriff
While I’m not sure of the exact process used by most manufacturers, nicotine can be very easily removed from the tobacco leaves directly using a combination of solvents in a technique called, unsurprisingly, extraction. By changing the solvent (aqueous vs organic, polar vs non polar) and the pH of solutions (acid vs base) you can selectively remove nicotine from the other components in the leaves. There are chromatography/filtration methods that can help separate and purify the product.
http://www.tifac.org.in/offer/tlbo/rep/st158.htm
Scroll down to the “Technologies for Nicotine based products” section, and one extraction method is described.
Anyone with access to the right chemicals can do it… though you’d need other instruments to prove you have obtained your nicotine at the end!
http://www.chemsoc.org/pdf/LearnNet/rsc/Prog_select.pdf This PDF has an analytical method for extracting nicotine.