Find a picture online of a receiver with his arms in the air about to make a reception. Print the picture out and take it to print shop. Have it blown up in black and white to about 5' (or the height you think might be appropriate for your kids). It will cost approximately $20.
With regular scissors, cut out the receiver and place it on the 3/4" plywood.
Place the cutout on one edge so you can cut two targets out of one 4x8 sheet of plywood. Trace the body of the receiver first, stopping at the top of his outstretched hands. Where his hands should be, use a five-gallon bucket and trace the circle out on the plywood; this is the inside circle of your target. Our figures had a 12" opening; however, you can make the opening any size you like.
Hammer a nail into the center of your circle and tie a string to it. Draw the string 4" beyond the initial circle and draw a second circle. Once everything is traced out onto the plywood, you're ready to cut (Image 1).
Use a narrow a jigsaw blade, which will make it easier to make sharp turns. Cut out the entire target keeping the blade at full speed. Cut around the outside circle for now. When you've finished cutting out the entire figure, drill a pilot hole inside the circle. Slide your jigsaw blade into the hole and cut out the inside creating the opening of the target (Image 2).
With the figure cut out, it's time to make a support. Take the 12' 2x4 and cut two 36" and two 60" pieces.
Note: The 36" piece is going to be attached on its side to the feet of the receiver. It will act as a stand with spikes to place into ground. The 60" piece will act as a back support and pull out to help the receiver stand up when footballs are thrown at it.
Take the 36" 2x4 and lay it flat, and drill 1/2" holes, 3" from both ends. Insert the spikes in the holes and hammer them all the way through. Place a flat metal protection plate over each spike. Use a mallet to hammer down them snuggly over the spike head, and secure them with 1-1/4" screws (Image 1).
Take the 36" 2x4 and place the 2" side under the toes of the receiver. Use 1-1/4" deck screws to attach it to the 2x4. The target should now be able to stand up but without the back support it will fall over when the ball hits.
Attach a 5"x4" block of 3/4" plywood length to the back of the receiver about 2" below the target. Screw one side of a strap hinge to the block. Open the hinge and attach the 60" 2x4 to the hinge. When secure, set the receiver up right with the 60" 2x4 at a 45-degree angle (Image 2).
Connect a thin metal chain from the middle of the 36" 2x4 to the bottom of the 60" 2x4, using screw eyes and S-hooks at both ends. The chain (Image 3) will ensure that the long brace stays in place and provide the support necessary to hold the receiver when balls are thrown at it.
Once the brace is properly attached, prime and paint your receiver as you wish.