Here is a project I made for my son, who is a tennis player. The wiring is easily adaptable if you want to add battery-powered Christmas lights to pretty much any object.
Step 1: Gather Materials
Strand of LED Christmas lights
Wire (I prefer solid core wire to stranded), 18 or 20 gauge
Wire cutters and strippers
Shrink tubing for attaching the wires
Heat gun or soldering iron for the shrink tubing
Garland and other decorations to suit your tastes.
Material for the base – I used wood.
Battery holders for the 2 AA batteries.
Switch – any kind you want. I used a knife switch because they’re more fun than a button.
Glue gun and/or other method of attaching wire to the racquet frame.
Step 2: Separate the Lights, and Create a Cardboard Template
Clip LED lights from a long light strand – leave 2 inches of wire on each side of the light. Pick out the colors you want - you might want them all or to create a pattern. I chose only red and green lights.
Strip about ½” of insulation from the ends of each lead.
Test the lights by connecting them to 3V DC source, such as your two AA batteries. Replace any that don't work.
Trace the head of the racquet onto a piece of cardboard, and mark where you want the lights to go (these marks are in pencil in the picture). A racquet has perfectly-spaced strings, so it's easy to line up lights on opposite sides.
Tape the first wire (green) to the outline of the racquet and use a marker to indicate where the lead from the light will connect to the wire. This mark will be offset from the pencil mark where you want the light to pop out of the racquet frame because of the length of the wire leads on each side of the light. See the picture for details.
When you're done with this step, you'll have as many pencil marks on the cardboard, and as many marker spots on the wire, as you have lights.
Set the lights down on the cardboard to ensure your marks are in the right place before proceeding.
Step 3: Wire the Lights
When the wiring is done, there will be two loops of wire going around the back of the racquet. For this project, the wires will be red and green. One wire will connect to the positive wire for each light, and the other will connect to the negative. When finished, the lights will be wired in parallel with each other, allowing a single 3V power source to light them all at once.
Start with the green wire. Strip the wire in the middle where the light’s lead will connect with the wire - you marked this with a marker in the last step. Use a very sharp hobby knife or razor blade. Shave the top of the wire until you can see the wire, then use the razor blade or the pointy end of the hobby knife to cut away the rest of the insulation. See the picture for details.
Put a light next to the wire, and twist the exposed end of the light’s lead to the bare spot in the long wire. Slide a piece of heat shrink tubing over the connection, and use the heat gun or soldering iron to shrink it. See the picture for an example.
Connect the rest of the lights to the green wire, making sure to orient the lights in the same way for each connection.
Prepare the red wire the same way. See the picture for all 8 lights wired together.
Step 4: Attach Wires to the Frame
Arrange the wires on the back side of the frame. I used twist ties to hold them in place.
Make sure the wires are not visible from the front of the racquet. Line them up so they are across from each other, using the racquet’s strings as references.
Warm up the glue gun. Release a few of the ties and deposit hot glue under the wires. Hold them down gently until the glue dries. Eight or ten inches of wire at a time is a manageable amount.
Step 5: Finish the Wiring
Connect the two ends of the green wire that looped around the frame of the racquet, using the same technique of exposing some of the wire with a hobby knife, and use shrink tubing to make the connection. This results in a loop of wire that goes around the frame and is connected at the handle. There is one one strand of green wire leaving the connection to go down the handle to the battery. See the pictures for details.
Do the same with the red wire.
Hold the green and red wires together and slide some shrink tubing onto them. Pull the wires taut and shrink the tubing to hold them together as they run down the back of the handle.
These wires will go down through the base and back up to be connected to a switch in a future step.
Step 6: Make the Base and Attach the Racquet
For this project, I used a piece of maple from my brother-in-law. I used a router and chisels to hollow out a section for the batteries and wires.
Refer to the pictures for details.
Drill a hole for the bolt that will attach the racquet to the base, and use a spade bit to widen it for a washer. Drill a hole in the bottom of the racquet to accept the bolt.
In one picture, you can see the wire coming down the back of the handle and into the base, and the shrink tubing that holds the wires together. You can also see the wires from the battery holders attached to the switch. The wires from the lights have not been attached to the switch yet.
In another picture is the completed base. I put a clear plastic window over the battery compartment to make it easy to change the batteries, and some felt feet. If you’re making these to sell at the local racquet club, you’ll want this to look better. (Don't forget to put in the batteries.)
There is a picture with a close-up of the knife switch after being attached to the base. The wires in the middle are the wires from the battery holders (I drilled a separate hole for them in the switch) and the wires on the end are from the lights.
Step 7: Enjoy Your Lights
Flip the switch to "ON" and watch your tennis racquet light up.
Step 8: Variations
There are many variations for this theme:
* Attach a tennis trophy figure to the base, or on top in lieu of the tennis ball. Or, use the techniques here to decorate a big trophy you already won playing tennis.
* Cover the back with garland to hide the wiring.
* Add more lights, ornaments, pictures of the recipient playing tennis, etc.
* Remove the strings and use red and green string or yarn to string the racquet in Christmas colors.
* Add Lego mini-figures playing tennis to the base.
* Wire the switch to a 2mm jack and allow your recipient to plug in the lights with a 3V adapter instead of using batteries.
* Come up with something else to light. Last year, I made a Christmas Tree Plunger, with a switch in the base. The bell of the plunger is a great place to put the battery holders and extra wires.