Bridal Shower Via The U.S. Mail

Please, please I need help. This is my second request. I am giving a Bridal Shower for my sister who is getting married in Las Vegas this June. Everyone lives across the country and I thought I would do a shower via the mail system where everyone that participates would mail their gift during a certain week so my sister would get a shower of gifts. Has this ever been done before? If so, any ideas on how to word the invitation. Thanks for your help!