Q: When is an oversized delivery box, some packaging, and a couple of old beakers not an oversized delivery box, some packaging, and a couple of old beakers?
A: When it is an enrichment goldmine.
If you look into the box, you might spot some tucked away bits of turkey. The idea is that your dog can have lots of fun, doing what dogs do best - using their noses to find things for their mouths. By adding different textures to a shallow box like this, it gives the dog a chance to snuffle around looking for his food. A nervous dog will need fairly quiet and soft items to snuffle around with, but the very act of being brave enough to stick his snout in, and get rewarded for it with a high value edible prize is enough to make him want to do it again, and again - slowly gaining in confidence as he goes.
Now here is the clever part. In the next session, if all went well, begin adding different textures, or something that makes a slight sound - such as plastic packaging, just one new thing at a time, until he again gets brave snuffling about, again gaining a little confidence as he goes.
Progress session by session adding in one new thing at a time, slowly increasing criteria until you might have squeaky things, bangy things, rattley things, and the dog is happy to snuffle about searching for his yummy prizes.
All the while you are doing this, (as long as you do not go too fast and give your dog too many new stimuli in one go - and take a step back if he does ever seem to be fearful of an object - the idea is meant to be relaxing - never to scare him or force him to take treats while under stress) he will slowly be entertaining himself, and hopefully enjoying using his nose and brain, gaining confidence with, and desensitising himself to different sounds and textures, while also learning to be optimistic that new things do not always mean something bad will happen - in fact quite the opposite, which he will then use to be better able to cope in the outside world too.
edit 22/9/18 - as a friend just said to me - you can also practice using a snuffle box in different locations too! This will also desensitise your dog to different places, sounds and events while still giving him an enjoyable activity. I would not, however, add in a new item to the box at the same time as using the box in a new location, incase the dog disliked either the item or the location and associated the two things. As always - take it at your dog's speed and never progress until they are happy and comfortable.