The Child Theme Wizard lets you create a new child theme without the need for additional tools, right from within the WordPress admin interface. Once activated you can find it under Tools - Child Theme Wizard.
Specify a parent theme, customise options such as title and description and click Create Child Theme. Upon success you will find your new theme under Appearance - Themes.
You have the option to include GPL License Terms if you wish. The Wizard will automatically create a thumbnail too. In future versions I may include an image uploader for this feature.
To find out more about Child Themes and why they are important please read
https://codex.wordpress.org/Child_Themes