Yesterday I've written a module for myself. Just an experiment. When I was feeling satisfied, I've created a repository on github, and pushed my code. My module and yii are on github. So I'll show you a "new" way to start our yii projects.
The yii2-field-range extension enables you to easily setup ActiveField range fields with Bootstrap styling. You basically can setup two attributes joined together like a single field with combined validation error block.