Building LCF meters is quite easy using microcontrollers. But measuring ESR of capacitors is a bit more complex as it is based on special conditions like using low voltage in order to measure in circuit and high frequency to eliminate resistance (reactance) of capacitor. There are few ESR meters that does job well, but most are analog meter based. We love digital so we could tweak functionality in software.

dr. le Hung LCFesR meter looks somewhat promising as ti does quite a lot. It can measure inductance withing range 10nH to 100H, capacitance from 0pF up to 0.1F, ESR from 0Ω to 30Ω. And additionally it measures frequency from 0.01Hz up to 8MHz. Pretty handy device built around Atmega88. Plans are available either 1 or 2 sided PCB with all through hole components.