This article describes a combined UV-photometer and fluorimeter constructed from 3 LEDs and a few wires, all held in place with Lego bricks. The instrument has a flexible design. In its simplest version, two UV-LEDs (355 nm) are used as light source and to detect absorption, and a third LED, in the visible spectrum (e.g., 525 nm), is used to detect fluorescence. Various experiments are described: fluorescence as a function of concentration and light source intensity; quantitative measurements of quinine in tonic water, using absorption and fluorescence measurements, with results in line with those obtained on scientific instruments; a demonstration of the inner filter effect reducing fluorescence at higher concentrations; investigation of the effect of drinking tonic water on the fluorescence of quinine in urine; temperature effects on fluorescence; chloride-ion quenching of fluorescence with result comparable to those previously reported; and, finally, a demonstration of phosphorescence.