Now, there is the need to put the LEDs somewhere, accoding to the original show:

The first (strange) thing that we need is to put the LEDs inside a bulb. It is known that you can cheaply buy from China a prepacket Christmas light with a Neopixel or the like already inside. But the holidays are coming, and there is no time to wait for the shipment. 

The first idea was to print the bulbs and the support for the LEDs, but with a reduced size, spiraled PLA print like this:

it took around 8 minutes. To keep the quality while increasing the size to the needed one, with a nozzle size compromise, it is not possible to go lower than 15 minutes per lamp. Which means more than 6 hours of printing.

The alternative

The second idea was to exploit some chinese Christmas lights. Once we found from eBay a general outdoor Christmas lights, the shape was good and we take the risk to try to recycle them for the alphabet purpose. Once arrived they were like this:

and with a big surprise, the lamps for external use are designed to be open, or at least these in particular:

So it was done. The base of the transparent bulb is large enough to host many LEDs package, like the 2020 size. So I tried with the APA102 LEDs, by cutting them individually, and solder wires of a length which should correspond to the spacing of each lamp, strengthening with hot glue e fit on the base of the lamp:

and by bending laterally the LED, fit into the colored bulb:

Et voilà:

Repeating the work by 26 times it is way less than 6 hours and it is very practical.

The next steps will be the firmware and the enclosure design.

There are moment in which the faith get lost, that is why I personally allocated some time to finish all the bulbs at once, to keep motivation and spinning momentum among friends that were willing to help, so that keeping hard we can go through all the steps up to the end!