>>8682623/toy/ would call this crowded but I love this. would just remove the mirror in the back. In all honesty the people crying about crowded displays are people who can't buy that many toys anyway. If you want advice, the best is to go to the source; Araki himself. He does a ton of group shots all the time, full fo characters clustered together, the trick is to have the character composition flow; never having two characters on the exact same level, leading your eye up and down slightly. The display does a fairly good job of capturing that.
And personally I think LEDs look bad I'd go with the lights in the standard installation. LEDs always look like a patchwork solution, not a natural part of the case.
