Here you can see how I hacked off the end of the NC.
Also shown are a couple of bits of foam, a length of fiberglass shaft, and a 35mm cannister.
The fiberglass shaft can be a wooden dowel as well.

Make sure the foam you use is open-celled to allow ambient air pressure to move through the foam to the baro
sensor on the Gwiz!  Closed cell foam will ruin your whole day.