Place soap base in microwave-safe measuring cup and heat on high for 30 seconds. Stir well. If not fully melted, heat for an additional 10 seconds and stir. Repeat for 10-second intervals until fully melted.

Add sugar and grapeseed oil. Stir well.

Place in microwave for an additional 10 seconds to help soften everything again.

Remove from microwave and quickly add soap colorant and essential oils. Stir well.

Immediately pour into ice cube tray.

Let set for about 30 minutes to harden.

Remove from tray and store in an airtight container for up to 3 months.