How to make grapefruit cello, courtesy of Chris Donahue at Casa Nonna.
Combine the Everclear, grapefruit peels, water, and simple syrup to taste in a container. Let sit for 30 days, and add the grapefruit zest. Let sit for another 15 days. Filter the limoncello (using a permanent coffee filter or cheesecloth strainer), and bottle.