Snapcraft is a delightful packaging tool
Snapcraft helps you assemble a whole project in a single tree out of many pieces. It can drive a very wide range of build and packaging systems, so that you can simply list all the upstream projects you want and have them built and installed together as a single tree.
For example, say you want to make a product that includes PyPI packages, Node.js packages from NPM, Java, and a bunch of daemons written in C and C++ that are built with autotools, snapcraft would make assembling the final tree very easy.
Snapcraft allows easy crafting of snap packages for the Ubuntu Core transactional system.
See the intro for details about the concepts behind snapcraft. There is also a tutorial. If you're interested in developing Snapcraft you should look at the hacking guide.