This board will let you hook 4 HC-SR04 ultrasonic sensors up to your Raspberry Pi for distance detection. The board supplies the sensors with 5V and makes the resonse safe for the Pi GPIO pins.. It's up to you how you arrange the sensors.
It also has 3 I2C headers to allow you to use more I2C devices with ease. While the 3rd one is intended for a small OLED device, you can use it for anything.
To build it, you'll need to solder headers, 330 and 470 resistors in the correct places and hook it up to your PI.
From there,see Github for more details