I use Adafruit's USB Isolater (https://www.adafruit.com/product/2107) whenever I'm programming an ESP or similar microcontroller in a live circuit so I don't have to worry about backfeeding power into my computer. It is an ESD-sensitive device and doesn't come with an enclosure though.
This simple enclosure snap-fits together and is easy to open. The hole in the middle is used to access the slide switch for low-speed/high-speed device mode.
I recommend printing using translucent PETG so the snap-fit tabs are flexible enough and to make it easier to see whether the status LED is lit or not.
The author hasn't provided the model origin yet.