Develop a Mac Application to find and replace files

I would like someone to develop an automator workflow for me. The task is to find images / videos / music files on an external hard drive, move them to a new location (folders called images / / videos / music respectively) and replace those files with a placeholder text file of the same name. The reason for this is I want the user to be able to browse the hard drive and see the locations of where all the image/movie/music files were and have now been replaced by text files for their peace of mind. I want the application to have options for both move and copy.