Use a vegetable peeler to remove the peels from the lemons, trying to remove only the outer yellow skin.

Trim away any large pieces of pith with a paring knife.

Transfer the lemon peels to a 1-quart jar.

Cover the peels with vodka and screw on the lid.

Let the vodka and lemon peels infuse somewhere out of the way and out of direct sunlight for at least 4 days or as long as a month.

Line a strainer with a large coffee filter and set it over a 4-cup measuring cup. Strain the infused vodka through the filter.

Prepare a sugar syrup by bringing 1 cup of water and 1 cup of sugar to a simmer, stirring to dissolve, and allowing it to cool.

Pour the sugar syrup into the infused vodka and stir gently to mix. Taste and add additional sugar syrup if desired.

Insert the funnel in the neck of one of the bottles and fill with limoncello. Repeat with remaining bottles.

Chill the limoncello in the fridge or freezer for at least 4 hours before drinking.