Once the felting process is complete, there's one more step you need to do in order to make your felted project come out right: blocking.
Blocking helps make your finished project the shape that you want it to be. In the case of my swatch, that's a square. If you were felting a bag or another large project, you might block it by stuffing it with newspapers so it is the shape you want and allowing it to dry.
Blocking a swatch is much simpler. Simply pin down one corner, then stretch gently until the sides are square and pin down the opposite corner. Repeat with the other two. Pin down the sides if necessary.
Allow your swatch to dry and celebrate successfully felting without a machine!