This recipe goes with Citrus Drop
Pour vodka into a well-cleaned 1 1/4- to 1 1/2-liter glass jar with lid. Thoroughly wash rinds of the grapefruit, tangerine, Meyer lemon, and Key limes. Slice fruit; add to jar (fruit should be completely immersed in vodka). Seal tightly; store in a cool (50-60°), dark, dry place. Let infuse 3-5 days (depending on taste; flavor will intensify over time), shaking container once a day. Strain vodka through a coffee filter or cheesecloth-lined strainer into a well-cleaned bottle or jar. Cover; store in the refrigerator or freezer for up to 4 months.