Hey you can try to create a child theme using this info here https://codex.wordpress.org/Child_Themes
I didn't have child themes in mind when I created lay theme. I think a great reason to do child themes is to be able to replace certain parts of the parent theme with your own templates. Like for example you want a post to be different, so you just have the file single.php in your child theme and that overrides the single.php of the parent theme. However, lay theme's frontend is just a javascript application, one .js file. So then the question is if it makes sense at all to do a child theme.
You can change lay theme a bit by using custom css, custom javascript and custom html, all of which is explained in the documentation on laytheme.com
