If both of you have Macs and are using the exact same version of iMovie you can create a new iMovie library, copy your project into it, and then put the library that contains the project on a thumb drive or other external drive that you can then physically transfer to your collaborator.
If the recipient is using software other than iMovie, or has a Windows PC, then the only way to share the project is to export the project as a movie file and send the standalone movie to your collaborator. Editing of it will be limited because embedded edits generally cannot be changed. However, perhaps your collaborator's software has the capability of splitting and trimming, adding titles, and so on.
-- Rich