For some time I have wanted to have a large scale LED based clock, this is the result. Using these files each digit is almost 11" in height. I used a strip of 30 LED's per meter and each segment has 3 LED's in it, while the colon segments house a single LED. An Arduino Nano runs the whole thing along with a DS1307 chip to keep accurate time - even when it is turned off.
There are three buttons. When the clock is running the hour and minute buttons will change the colour. The setting button, pressed briefly will change the colon colour.
The clock can have different colours for the hours, minutes and colon, you can pick from red, orange, yellow, green, cyan, blue, purple, magenta, "harlequin", colour fade and white. The harlequin is where each segment is a different colour and fades across the rainbow. colour fade will fade the whole digit through the rainbow.
If you press the setting button down for 2 seconds the clock will go into a setting mode, allowing the changing of the time (press and hold the hour/minute buttons to change the time). The setting button can be briefly pressed to turn DST on and off and held for 2 seconds to set the time and switch back to time display.
I am still working on this. Also my programming skills are self taught and may not be the most efficient methods! It also needs a number of support libraries, check the #include lines for which ones.
I used black PLA for the segments and a white PLA for the diffuser. As the diffuser is <1mm thick the PLA allows the the light through enough while spreading it out.