Find a suitcase that will accommodate all of your pedals. You should have enough space to set the pedals at least 4 inches apart. You don't want a crowded space because you need to be able to easily place your foot on the pedal you want while on stage.
Buy foam rubber that is at least 4 inches thick. You can buy this at art supply houses. Use a knife to cut the foam rubber into a rectangle that will fit snugly into the suitcase. Make sure it does not slide out when you turn the suitcase upside down.
Cut small rectangles in the foam rubber. Make them slightly smaller than the dimensions of your pedals. You can place each pedal on the foam rubber and trace around it with a marker, and cut just inside that line. This will allow the pedal to be pushed down into the foam and remain held in place by the snug foam rubber. Do not cut all the way through the foam to the bottom of the suitcase. Cutting all the way through will reduce foam under them, which provides a cushion.
Cut grooves for cords and plugs. You want to be able to plug in the cords to the jacks on the sides of the pedals, so cut a space by each pedal that will allow you to do this.
Close the suitcase lid and shake the suitcase. Your pedals should remain in place. You should even turn the suitcase upside down to make sure the pedals do not come loose. If there are any problems, cut wedges of foam rubber to stuff around the pedals to keep them in place.