Does anybody think they could do it? Has it been done already?
CAN IT BE DONE!? Could you use a LCD or not because it has a built in CRT!? Would need a wide screen CRT sideways.
Yeah, it's impossible. The Vectrex uses a special type of monitor, a vector monitor, which operates differently than your typical "raster" monitor, what televisions, arcades, and computer monitors use. Some arcades, such as Asteroids, use vector monitors, as they allow the games to easily draw objects that can be rotated and scaled without distorting the original image (and through the hardware too, which allows for very fast image manipulation); this type of graphic is what CorelDraw uses so that artists can create images for signs and banners that can be blown up nigh-infinitely to any size without losing picture quality. Raster monitors are what 99.999% of CRTs in the world are; any tube-based TV and just about any monitor will use one of these, and they cannot handle hardware-based vector graphics.
That "Vector Monitor" is a CRT, a bit like an oscilloscope. And it's kinda big. You'd need some serious batteries for that thing. It might be fun to integrate into some geeky art thing, but I don't think you could make it very portable.