The frame for your clock can be as simple or as fancy as you wish. Here, a minimalist and inexpensive option is shown, creating a thin channel in which to hold the NeoPixel strip and a small cardboard base to keep it standing.
Cut three long, thin strips of cardboard.
Glue them together to create a channel that will hold the NeoPixel strip.
Lay the NeoPixel strip into the channel to test its fit.
Cut three rectangular sections of cardboard.
Make a small square hole through two of them and cut a longer channel out of the third.
Glue the three pieces together, putting the channel on the bottom
Bring it Together
Glue two strips of cardboard on the base to hold the bottom of the acrylic in place.
Use hot glue to affix the NeoPixel channel to the base, centering it over the hole cut for the the strip.
Thread the NeoPixel strip through the hole in the base, pulling it all the way through so the last pixel is at the top of the channel. Keep in mind the bottom pixel will be hidden in the base of the clock; it is ignored in the code, this is ok.
Add two more strips of cardboard to the bottom of the base, pinning the end of the NeoPixel strip so that it comes out the back.
Slot acrylic piece into place.
As a final touch, once the acrylic piece is in place, add a dab of hot glue to the top to keep the acrylic held tightly against the the NeoPixel strip.
Power on your clock and you should see the time pop up!