I'm just learning to build pedals, and just had an idea... so maybe this is a dumb question... but is there some sort of 2-pin jack (header? I don't know the terminology) that I could put in place of the yellow LEDs on the LDR circuit and then I could "plug and play" with different LED colors, to see how it affects the sound without having to de- and re-solder the LEDs every time?
(I could definitely hack it somehow, but I'm just wondering if there's a specific part that is the exact perfect dimensions for this)