The best part about this customization is how it leverages the cargo area feature Hasbro built into the flooring. Even Mr. Nomadscout can tolerate this kind of "nondestructive" customization. This comes from Mister Skeezler on Instagram. Besides the short video, be sure to click the arrows to scroll through the images on how he installed the device.
Update: Mister Skeezler let us know in the comments below the sound chip used is available on Amazon.