How do I change the size / aspect ratio of my template?

When creating a new template, it's possible to set a custom canvas size. It's also possible to modify an existing template to change its size.

New Template

1. Head to your project
2. Hit Create a template 
3. Click the drop-down menu under Size format and select Custom
4. Enter the Width and Height you want and click Save

Existing Template

1. Head to the template you want to modify and click Edit Template to access the template editor
2. On the left panel below the template name, click the current template size/dimensions to change it
3. Enter the Width and Height you want and click Save

Note: There's a maximum canvas size of 5000x5000. Check out Why is there a maximum size limit? for more information.