I just came up with an idea for a mod which I have essentially been looking for for ages. I don't know whether a mod or a mod like this is available right now, so if you have any ideas please comment below!
This mod would essentially allow you to place certain LED light fixtures similar to the signals used in the mod 'Railcraft'.
There would be a connector block (exactly like in Railcraft) which you can connect to the light to control it (including something like the Analogue Controller Box, which means different setups for different incoming redstone strenghts).
Now for each different setup of redstone input you would be able to cutomize your own setup of which diodes would light up. There would be quite a lot of diodes in the light block.
You'd be able to use them in all kinds of different projects, such as scrolling text, shop OPEN and CLOSE signs, and (what I want to use such mod for) signals which look not dissimilar to those found in Railcraft (maybe add some kind of black encasing like in Railcraft)
Example of signal encasing (you'd be able to select which parts of the light light up to make different shapes and choose your color such as white, green, red, blue, etc.):
Example of what you could make out of it:
Thank you so much for reading! I really hope this could possibly be a mod in the future.