To add or customize the template selection in the Playground, simply add templates to the project named Playground in your Bannerbear account.

Alternatively you can directly access the Playground from any template on your account — look for the playground ball icon.

You can customize the templates in the Template Set at any time. Go to Bannerbear, edit the templates and save your changes.

You can also add your own templates to this template set, in any size you like. Include some or all of these layer names / types for compatibility with this Tweet Image tool.