If you haven't installed the switch (If you have chosen to use it) do so now. Mark the box with a sharpie or a lettering machine for on / off. Next if you've chosen the same battery box you'll note it is really close to the same size as the Altoids tin. Slip the side with the leads into the box and apply pressure on the opposite side, you'll distort the box slightly but it should go in, On my box the battery contacts were recessed so there was little chance of shorting out the wires. Now put your batteries in and close your box, you're ready to enjoy your Altoids Pocket Super Solderless Breadboard Junior. Thanks for checking out my second instructable.