There is a design published by Nathan Ramsden as referenced here from 2016 which I used in my 14-envelope follower build as part of my analog vocoder.
It works nicely, but has a drawback that the input voltage must exceed the threshold voltage of diode D1, otherwise nothing happens. So for small signal levels this could be problematic. A Schotky diode would lower that, or a bias current could possibly help. The attack and decay pots are handy although I have found that the attack pot gives you only little range to work with. This in fact is to be expected: if the attack time is set to a large value, the input signal might have lowered in voltage before the attack time passes and then there will not be much signal you can control with the decay pot. This is especially so with impulsive signals like drum beats etc.