Day Three Hundred and Sixteen
I went in search of more resonant metal in public places today, and endured the strange looks from passers by while I banged away on a Brunswick post box. There's a hydrant I have in my sights for tomorrow, too. Plus flying fox loops from yesterday, pitched down and with some delay and vocoder effect. I've found vocoder pretty effective with metal sounds, although traditionally used for voice - the result is quite different here.
Also I just learnt that the vocoder was initially contrived to disguise voices in radio transmissions in the 1930s. The scrambled sound wave would then be securely unscrambled at the other end.