Attaching zip files to responses in a REST mockservice

Hello,

We'd like to deploy a REST mockservice in a Tomcat server, with one zip file attached to each response.
I've seen that file attachment is available for SOAP mockservices, but not for REST. What's the best option to do that ?
We figured we should use a Groovy script to load the files and dispatch the responses, but we're not sure which path we can use to locate and load our zip files. 

Many thanks for any help you can provide!