Place the red, white, and blue chocolate melts into separate bowls. Melt as directed on the package and mix until smooth.
Pour the melted chocolate into icing bags. Cut a small tip off the end of each icing bag.
Apply a line of melted white chocolate along the long side of a wafer cookie. Take another wafer cookie and press it into the melted chocolate, keeping the two cookies flat on your work surface as the chocolate continues to harden.
Fill in the blue rectangle completely with melted blue chocolate.
Immediately sprinkle the white sprinkles on top of the blue chocolate before it hardens.
To make the red stripes, use the grid lines on the wafer cookie as your guide. Apply a stripe of melted red chocolate so that it is the width of 1 gridline, leaving a blank line between the red stripes for the white chocolate stripes later. Let the red chocolate dry for about 30 seconds before applying the white stripes.
Fill in the white stripes with the white chocolate. Let dry completely for about 30 minutes or longer if needed.