Toilet fizzies

Fizzing baking soda and citric acid pucks with essential oil that freshen the bowl between cleans.

NEVER use these with bleach or bleach-based toilet cleaners, before or after. Citric acid plus bleach releases chlorine gas. Flush thoroughly between products.
Never mix bleach with ammonia or rubbing alcohol either.
Wear a dust mask when measuring sodium coco sulfate and citric acid. The fine powders irritate lungs and eyes.
They look like candy. Label the jar 'Toilet only. Not food' and keep it away from children and pets.
These freshen but don't disinfect. Don't use them on natural stone, because citric acid etches it.

Steps

Put on gloves and a mask. Whisk the baking soda, citric acid and sodium coco sulfate together, breaking up all lumps.
Add the essential oil drop by drop while whisking.
Spritz witch hazel or alcohol a little at a time, mixing constantly, until a squeezed handful holds together like damp sand. Water or too much liquid starts the fizz early, so use as little as you can.
Pack the mixture tightly into the molds.
Let them dry for 24 hours in a dry room, then unmold.
Store them in a labeled airtight jar.
To use, drop one in the bowl and let it fizz for a few minutes, brush, then flush.

Bombs fizz, swell or grow bumps in the mold: Too much liquid, or water-based liquid. Use alcohol or witch hazel, a spritz at a time, and dry them in a low-humidity room.
Crumble when unmolding: Too dry. Spritz a little more and pack harder.
Weak fizz: They absorbed moisture in storage. Keep them airtight, and use fresh citric acid.
Clumping powder while mixing: Humidity or damp bowl. Whisk and sieve the dry ingredients before adding any liquid.