Bend your NeoPixel strip into a ring with the pixels facing outwards. Use a cable tie to secure the ends together.

Use another cable tie to secure the pixels and wires to the board so that the ring dangles below. This is a little trickier with the QT PY since it's so small, but it's do-able.

Be sure to catch the wires inside the cable tie. This will provide strain relief so the wires won't accidentally pull out of the board.

Now it's time to add your tentacles. The tentacles will diffuse the pixels for a nice soft reflective look.

I tied a couple pieces of tubular crin to the bottom of my pixel loop, then cut a small slit in the sequin fabric and slipped the miccrocontroller through, so the fabric hangs on both sides of the pixel strip, covering the lights completely.

Slip the end of your USB cable through the hole in the top of your jellyfish head. Plug it into your board. Add another cable tie around the board and cord so the weight of the jellyfish is NOT hanging from the USB port. 

Add another cable tie on the outside of the jellyfish around the cord so the microcontroller stays in place.

Pull a bit on your cord and make sure that all the strain is taken by the cable and the cable ties, and that nothing is pulling unduly on the LEDs or the microcontroller.