Mix.
Press the mixture into your silicone mold firmly pressing down on any corners or sides.
You will know that there is enough water when you are able to grab the mixture with your hand and it's able to hold form, not falling apart. Avoid spraying too much or it will start to fizz. Think of it as slightly dampening the mixture. This recipe makes about 12-14 medium sized toilet bombs.
Recipe from https://sweetnaturesbeauty.com/