In Infigo, you can enable the Saved Projects feature so that your end users are able to create their artwork and save it for later purchasing/editing.

• To enable this go to the Admin Menu > Configuration > Settings > Order Settings
• Tick the setting "Saved Projects Enabled" (around half way down the page), and then click Save (top right corner). 

Now, when your end users edit their product, they'll see a button saying "Save as Project". 

If you'd like to edit the text displayed in this button you can do so in the language string  VariableEditor.WorkflowTools.SaveProject