From the MAKE Flickr pool

Matt the modulator built a deluxe substitution box for experimenting with different resistor & capacitor values for circuit bending. Features include -

1. Resistance pots (4k7, 100k, 1m)
2. Capacitance – 12 caps selector
poly 47-pf, 100-pf, 470-pf, 1-nf, 4n7 nf, 10-nf, 100nf, 1-uf, 1uf
elec 1uf, 4.7uf, 10uf, 100uf
3. LED
4. Signal tracer simply a 1w amp maplin kit to trace audio signal in a circuit.

Have a closer look at the innards on Flickr.