Import from PSD files
First, you can import designs created in... Adobe Photoshop! Yes, your designers don't have to learn any new tools, they should just follow some guidelines to create designs compatible with Customer's Canvas.
Migrate through API
Another option is to use an API to generate a template file. It is especially convenient when you are migrating from an existing system which already has a large amount of templates. With the API, you can automate the template migration.
Design in visual editor
Last but not least option is using Customer's Canvas to create new (or edit imported) templates. Yes, Customer's Canvas is great not just for your customers but also for your own staff.
For many print products using great fonts is a key factor. Customer's Canvas can use really sophisticated fonts of any format, even if browsers don't load them properly - PostScript, WOFF, TrueType, Open Type. No need to install them in the system, it is enough just to put them into a special folder on your Customer's Canvas server. Fonts from templates are grabbed automatically.