To download Polymer, its dependencies and such, use bower, then, in a new directory, type in the command line
bower init. (You can press enter -- except for the name -- at all the prompts if you want.)
$ bower init ? name: somename ? version: 0.0.0 ... ? Looks good? Yes
bower install --save Polymer/polymer#^1.2.0 which will pull the latest Polymer 1.2 minor version, its dependencies, and place them all in a directory called bower_components.
Now let's create an index.html.
<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <script src="bower_components/webcomponentsjs/webcomponents-lite.min.js"></script> <link rel="import" href="bower_components/polymer/polymer.html"> </head> <body> This does nothing at the moment, except pull in webcomponents and polymer. </body> </html>
And we are, at least, setup, if not actually using polymer as yet.