I made the banner on my computer and home printer. Used different fonts with different colors for each letter and printed two letters per one 8.5x11 sheet. Cut and then stapled on ribbon. It took me about 15 minutes to make. Super easy.
Made monster truck costumes for each of the children, so they could have a "monster truck rally". Bought small shipping boxes--cut the flaps off one side. Spray painted top part red, bottom metallic. Spray painted small white plates black for the tires (although you could just buy black plates). And then painted on truck decal and headlights. Punch holes and strung black twine. The back of each "truck" had a "license plate" with the children's name on it that I made in Word.
We were lucky enough to have a ride-on monster truck, so the children had fun rallying it down our driveway.
Why not add some water into the mix? It's summer. The backyard was the "monster pit" with lots of obstacles.
He's a very happy boy. He already asked me if he could have a dump truck party next year. Oh, his love for the four-wheels.