Movie: http://youtu.be/TVAAIxcCAu0 This is an improved version of Filament Width sensor thing #636420, based on shadow casting idea by Flipper's #454584. Now this sensor measures the filament width in three directions: -45, 0, and 45 deg. Three LEDs are sequentially light up and the sensor measures shadows from each direction. It (hopefully) compensate out-of-round filament shape. 45deg measurement limits the maximum measurable filament width around 2.5mm, so, unfortunately, this version is only applicable to 1.75mm filament. For 3mm filament, consider upgrade the line array sensor to wider one, such as TSL1402.BOM) 1 x Arduino Pro Micro board 1 x PCB 1 x TSL1401 Line scan sensor 1 x 1Kohm resister (SMD 2012) 1 x 10nF ceramic capacitor (SMD 2012) 1 x 0.1uF ceramic capacitor (SMD 2012) 3 x 200ohm resister (SMD 2012) 3 x 10uF multi-layer ceramic capacitor (SMD 2012) 1 x 2x3 pin header 1 x Molex 5046 (right angle, male type mount) 1 x Molex 5051 (female type socket) 3 x High-brightness LED (5mm radius) 8 x 2mm x 8mm sheet metal screw