My nephew dumped an "H" sign character off at the shop. I just saw it there one day. I asked him about it, and he said, it was gift for a friend ... after it was converted to LEDs. He asked if I could do it, and also make it respond to sound. I said, sure, and that I actual make a kit, to do the very thing he wanted. I peaked inside, and found the following:
A big neon H, about 2 x 2 feet (or a little bigger than half a meter a side).
So my payment for the conversion, is that I get to keep this large piece of neon filled glass. Btw, its lit up by an old ignition coil, driven by a 555 chopper circuit.