Here's a board I made to quickly prototype effects pedals. It is basically a noisy cricket paired with something like a Beavis Board and a few extras. The amp is on the left, and provides a headphone jack, 1/4" pre-and post-amp outs, or you can just use the built-in speaker. On the right is a breadboard and some terminal blocks. There is a 1/4" stereo in jack that cuts power when the cord is removed. There is also a 2.1mm jack for power that bypasses the internal 9V battery. Down the center are some pots of various resistances coupled with on-off-on switches that put additional resistors in parallel with them to change the range of the pots. I have them set to 250K/1M/500K, 50K/250K/100K, and 1K/10K/5K. There are also a couple of DPDT switches for using directly with the effect. At the bottom is a standard 3PDT stomp and indicator light.
Each pin of the pots and switches is connected to one side of the terminal blocks. Input is connected to the top terminal, and output is connected to the bottom terminal. Power is connected to the left power rails of the breadboard. I 3D printed the knobs and speaker grill.
On the breadboard in the pictures are a couple of effects that I've been playing with. The top one is the Dan Armstrong Green Ringer. At the bottom is the start of a looper made from a Teensy 3.1 with the Audio Adapter Board. The tone from it was less than perfect (and I'm only a drummer in a past life, really), so I put a quick and easy small buffer in front of it.
