Richard Kline wrote in with his detailed and well-written tutorial on how to create your own ginormous 5×7 display.

I built this large display, which is designed to mimic a common 5×7 LED readout, out of pink foam insulation and sundry other bits from Home Depot. The LED’s are diffused 5mm RGB’s wired together with a cut-up IDE cable…both are cheaply available in bulk from Ebay.