Wash your grapefruits. Using a duller peeler, peel just the top layer of the skin off the grapefruits. Avoid peeling off any of the white pit as much as you can. The white parts will make it bitter. I have found that cheap peelers are not very sharp to begin with and perfect for this. If you do get a lot of white on the peels, use a knife to scrape as much as you can off. This is not a fun process, so the cheap peeler is the best approach.
Place the peels in a large, 1 gallon glass jar that has a lid. Pour the vodka and everclear into the peels.
Place the lid on the jar and let it sit for at least one week, up to four weeks. Keep it out of direct sunlight.
When this step is complete, make the sugar water. Combine the sugar and water in a medium saucepan and heat over medium heat until the sugar is dissolved. Let the sugar water cool to room temperature.
When cool, add the sugar water to the peel mixture in the gallon jar. Cover and let it sit for another week.
After it sits for a week, strain out all of the peels and bits that are in the liquid. Funnel the grapefruit-cello into the glass bottles with stoppers. Store in the freezer. The grapefruit-cello can be served straight or as part of a mixed drink. Taste the grapefruit-cello so that you know how strong that batch is based upon how much sugar water you use.