When there is no guide file, you can make your own by taking a screenshot of the design tool view and cropping it to the provided guidelines as exactly as you can. Then you can make it larger in your photoshop, the proportions will stay the same, and use it as a base layer as a guide. Here's one I did real quick for the basic 11oz Mug.
And then here's the .png I made to use as guide layer in Photoshop:
PS -
You can upload the .png guidefile to the Zazzle designer and it's a perfect fit so you can use it as a guide for designing in the Design Tool too and not just before uploading a finished design. Then delete the guide layer before publishing.
