Adafruit 1.2 4-Digit 7-Segment Display w/I2C Backpack - Yellow : ID 1269 : $17.50 : Adafruit Industries, Unique & fun DIY electronics and kits
DIY Large Seven Segment Display « Matt's Hacks
HowTo: Electronics - Build seven segment LED digit called "pxlDigit" from WS2812 LEDs - Nerdiy.de - Nerdy DIY HowTo's about electronics, 3D-printing and more.
DIY Large LED Lit 7 Segment Display : 10 Steps (with Pictures) - Instructables
How to make Seven Segment Display at home - YouTube
Mechanical 7 Segment Display Driven By An Arduino Mega - The DIY Life