Box mock-ups can be used to create a realistic presentation of your designs. Here is a square box mockup for you to use on your packaging projects. All you need to do is place your artwork inside the smart layers hit save and you are done. You can as well change the color of the mockup and background of the box to meet your needs.
Thanks to Pixeden for always releasing high quality mockups to the community. Their website too has loads of useful design resources. Check them out.