I must have some sort of reputation, because I recently received two fantastic gifts in the same theme. The first, a fascinating and extremely comprehensive book on illumination from 1942, was very thoughtfully sent by @MakeAugusta. The second, from the educational nonprofit where I volunteer, is a detailed LED diagram mug. Last summer I taught campers that LED stands for "Light Emitting Diode," and next summer I'll be able to quiz them on an LED's detailed internal structure!