Apollo Server sandbox explorer source code

I am trying to build a UI for apollo graphql. What apollo sandbox provide to quickly select fields and query is what exactly I want. But it is techy for non-IT person. I want to add some tweaks based on my requirements and deploy the modified-sanbox/my-own-ui on my server.
I am not sure if sandbox UI is publicly available or not. And If not how can I create my own sandbox like look ?