A growing number of spirits lovers are experimenting with “infinity bottles.” The practice involves taking a bottle of liquor that’s not quite full and strategically topping it up with pours from other bottles to make unique blends that can’t be found anywhere else.

As the bottle drains over time, a splash of this or that is added. Ideally, the bottle is never completely empty, hence the “infinity” name.

Although there are no precise rules, most people stick to a single category of spirit. Whiskey infinity bottles are the most popular, although rum infinity bottles have gained traction, too. We’ve even heard tales of at least one “gin-finity” bottle.

If you want to elevate your whiskey blending skills, it’s not about throwing odds and ends in a bottle, but finding nuance and balance.

For collectors, the infinity bottle can be a creative way to try the art of blending at home. It’s a DIY version of how professional spirits producers mix various barrels, finishes or vintages artfully to create desired flavor profile. It’s also a way to use up those almost-empty bottles that sit in the back of your liquor cabinet. The goal is to create a custom blend that’s more than the sum of its parts.

The concept is based loosely on the solera system used to make Sherry and some spirits. Small fractions from different vintages are blended together, and as the oldest liquid depletes, a younger vintage is added. In theory, some of the oldest liquid is always part of the blend.

Joe Beatrice, founder of Barrell Bourbon, drew inspiration from this trend to create an “infinity barrel,” an infinity bottle writ large. His initial foray combines five different types of whiskey in a single barrel, including Scotch, Irish whiskey and even Sherry-finished rye, to create a mashup that defies the usual whiskey rules.

Beatrice plans on continuing to add to this barrel over time. We asked the master blender for guidelines on how to create the ultimate custom whiskey blend at home.

How to blend your own whiskey

Pick a base. “Start with a whiskey that really appeals to you,” says Beatrice.

“Everybody has their go-to, their favorites. What whiskey profiles do you like? Do you like the American corn whiskey flavor, or the malt flavor of Scotch? Irish whiskey? Any of those are very dominant, and can dictate the flavor of the entire bottle.”

Beatrice recommends labeling your bottle early on, so you can start listing what goes inside.

Add a second whiskey. For optimal impact, Beatrice recommends selecting a whiskey that offers a contrast to the base. Did you start with a sweet, vanilla-forward Bourbon? Maybe try a small measure of smoky Scotch to a counter. Was your base a mellow, fruity Irish whiskey? Perhaps add a spicy rye. Taste it, and see what you think.

Feeling bold? Add a third whiskey, but don’t go overboard. “Try a little bit at a time, see how that goes,” says Beatrice. “It gets exponentially more complicated as you add other whiskeys.” Have a bottle of Sherry-finished whiskey with less than a dram left in the bottle? Add it, but just a little.

Let it rest. “It takes a while for whiskeys to marry,” says Beatrice. After you add to the blend, let it rest overnight. Sample it again and see how the blend has evolved. Beatrice considers 12 hours to be the absolute minimum to allow the whiskeys to combine.

A word of warning: Don’t shake the bottle. It “makes the whiskey really angry,” says Beatrice. However, it’s O.K. to gently rock the bottle if you feel the blend needs a little integration.

Have patience. If you want to elevate your whiskey blending skills, it’s not about throwing odds and ends in a bottle, but finding nuance and balance. “Just because things taste good, they might not taste good together,” says Beatrice. “It takes a lot of work and experimentation and trial and error to do it.”

Think young. What if you create a blend, but you don’t like it? Add a very young whiskey. Beatrice suggests a one- or two-year-old whiskey. “It will neutralize some of the flavor if it’s gone astray a bit.” Let the blend rest, and try it again. “You can almost always save something,” he says.

Know when to stop. It’s tempting to keep tinkering, but when you arrive at a flavor profile you like, hold fast, Beatrice says. “You have to have the restraint to say ‘This is it. Don’t add anything else. Stop here.’”

Repeat. As the bottle depletes over time, consider what else to add to your blend. After all, an infinity bottle should never be completely empty, but it should keep getting better as time goes on, into infinity.