The Thai tradition of making a wish and sending a floating candle down a river is something you can take part in and customise to your own traditions. Using light, biodegradable materials such as wood and paper are ideal for this project, because they float and won't harm the environment like plastics. You can also use this project for making decorative, floating lights for a summer party. You only a need a few inexpensive materials.
Apply a line of hot glue to the right side of a craft stick and affix the left side another craft stick to it, with the ends lined up. Allow the glue to cool and solidify for 10 minutes, then glue another craft stick to the left right side of the last one. Repeat this until you have a flat square of 8 or 9 craft sticks. Repeat this step to make a second square of 8 or 9 craft sticks. Don't leave any gaps between the sticks and seal the seams with glue.
Glue the two squares together. Run a line of hot glue along the length of a lightweight stick at least 1cm thick. Attach the stick to the back of one of the squares, close to an edge. Glue another similar stick to the opposite end of the square, so the two sticks are parallel and on the same face of the square. These two sticks need to be the same length as the width of the craft stick squares. Wait for the glue to dry.
Glue the other square to the sticks that you attached to the first one to finish your miniature raft for the candle.
Cut a paper cup with a utility knife or pair of scissors, so it is about 1/3 its original height. Place a tea light candle in the centre of the cup and trace around the candle with a pen. Carefully cut along the line you traced with a sharp utility knife. Since the bottoms of most paper cups are slightly raised, this gives you a holder to put your tea light candle in, so it stays in one spot.
Dab some glue around the bottom of the cup and affix it to the centre of the top of the raft. Decorate around the raft with flowers if you wish. Light the candle and place it in the hole you cut in the centre of the cup when you are ready to float it down the river.