An Instructables article which helped me make this pretty easily ; was the wiring diagram found here:
Step 1: Tools & Parts List
-Soldering iron & rosin core solder
-Drill w/ bits
1x Project Box (plastic / wooden / metal)
1x DPDT switch (can be a sw like I used, or get a DPDT footswitch)
3x 1/4 Mono jacks
2x 5mm LED's
2x LED Holders
1x 4,700 ohm Resistor
9v Battery Holder / Terminals
22 Gauge Wire
Step 2: Wiring Your A/B Box & LED Wiring
*Connect the Tip on output A jack to the 1st and 6th prong on the DPDT switch.
*Next, connect the tip of the Input jack to the 3rd prong on the DPDT switch.
*Connect the tip on the Output B jack to the 5th and 2nd prongs on the DPDT switch.
*Finally, connect the sleeve of Output A to the sleeve of the Input Jack, And then connect the input sleeve to the sleeve of the Output B jack and finally connect that to the 4th prong on the DPDT switch.
I am using 22 Gauge Wire for this project between audio connections.
** Note: If adding LEDs, connect your 9v Battery's (+) to the (+) line of both LED's (that's the longer pin , or the smaller of the two internal filaments if you didn't know) with a 4.7k resistor in line before the LED . DO NOT FEED AN LED 9V, without a 4.7K ohm RESISTOR. Next connect the (-) of ea LED to the 'bridged' connectors on the switch found in this diagram. When switched into either on position, now the LED's will light up with the corresponding jack. **
Step 3: Finishing Up / Enclosure Installation
Once you are satisfied with how the A/B box is performing, now it's time to house the materials. I choose a carved wooden box to install my components ; but you can find project enclosures on the net or build your own from scrap metal. If using metal, be sure to insulate the metal before installing your components to avoid them grounding out on your enclosure.
The switch I used isn't right, but looks and works well, because it's flush mounted with the surface.
You can accomplish this by drilling the top with a larger bit on the outside then mount your switch after drilling out the center hole. This allows you to quickly kick the switch on/off/on ; but I highly recommend buying a DPDT Stomp switch if you are planning on kicking it around on the floor.
The DPDT Stomp switches :
..... are much more effective if you plan on gigging with one of these.