To build your blaster and target, place the AAA batteries in each pack, then plug them in, and turn on the packs.
Use zip ties or double stick foam tape to connect the boards to the battery packs.
You can add a barrel to your blaster to narrow the IR beam spread. This will actually make aiming at your target much more challenging -- and fun! You can use a straw, a pen barrel, even a rolled up tube of paper.
Simply place the barrel over the TX LED on the Circuit Playground Express. You can hold it in place while playing, or stick it on with some poster putty.
Have fun, and remember, when a target is full you can just reset it and start all over again! You'll be an IR sharpshooter in no time!!