title_body: How do I repack a .mobi file?
upvoted_answer: KindleUnpack is primarily intended for debugging KindleGen issues. If your original Kindle books is an AZW3 book or a MOBI book generated with KindleGen, you can edit it with Calibre Editor. 
  
  Simply select the book in Calibre, right-click it and select Edit book. This will automatically unpack the book and open it in Calibre Editor. If you save the book it'll be automatically reassembled.