Certain opioids and hallucinogens have such a tiny active efficacy that they fit on a square paper blotter... First the compound is made up into a liquor (Ethanol based) solution for proper microgram measuring. Then the dissolved substance is dropped onto the blotter paper and a UV light shined upon the wetted blotter to quickly dry it and then drop some more of the solution till the desired uug amount has been properly soaked in the square perferations for each blotter piece on the strip or sheet.