Prepare the sodium alginate bath

• Combine the sodium alginate and distilled water in a large airtight bowl using the immersion blender.
• Let the bath sit so the bubbles dissipate.

Build the cocktail

• Combine the vodka, coffee liqueur, simple syrup and espresso in a bowl.
• Blend in the calcium lactate with the immersion blender until super frothy, then pour immediately before it separates.

Freeze the cocktail pods

• Pour the frothy cocktail into the ice cube trays, leaving the foam on top.
• Freeze until solid.

Form the pods in the alginate bath

• Warm the sodium alginate bath to about 120 °F and set out two bowls of cold water.
• Drop one frozen cocktail pod into the bath and gently stir the water with a spoon, without touching the pod until the membrane has formed.
• Flip the pod so the foamy top gets coated.

Rinse the pods

• Lift the pod out with a slotted spoon and wipe the bottom of the spoon with a paper towel.
• Transfer to the first cold water bath and rinse thoroughly by stirring the water, then repeat in the second bath.

Serve or store

• Serve the pods right away, garnished with a coffee bean on top.
• Or store them in a mason jar filled with a holding liquid made from the cocktail, minus the calcium lactate.