Step 1: Materials
Qty 1 --- Altoids Tin. See Note 1.
Qty 5 --- 1/8" (3.5mm) Stereo input Jacks, Radio Shack part 274-249 or equiv.
Qty 8 --- 1k ohm Resistors, Radio Shack part 271-004 (5-pack) or equiv. see Note 2.
1 foot --- 22-30 gauge solid hookup wire, stripped bare
Note 1: A normal Altoids Tin can take 4 or more inputs, this example assumes 4 inputs. The Altoids Gum tins can fit 3 inputs comfortably. Adjust the number of jacks according to:
# of Jacks = 1+ # of inputs
and number of resistors by:
# of Resistors = 2 * # of inputs
Note 2: All resistors (2 per input channel) should have the same value, which can be anything between 1k and 10k ohms. Higher values result in a higher volume drop. Also, the resistor power rating can be 1/8 or higher. This circuit runs no power through it, so there's no need for bigger than 1/8 w, but use whatever you have handy. Bigger power rating = bigger size.