To make a rainbow balloon arch, use helium to blow up balloons of different colors, tie them together by color group and attach the color groups together to form an arch. It takes approximately 96 balloons to make an average-size arch. For a rainbow arch, suggested colors are pink or red, orange, yellow, green, blue and purple.
There are only a few supplies a person needs to make a balloon arch. Gather 16 balloons of six different colors, helium tanks, balloon weights, curling ribbon and scissors.
Step 1: Inflate and tie the balloons together
Begin by inflating the balloons, one color at a time. Tie the balloons together in clusters of four. Cut a piece of ribbon approximately 48 inches long, attach it to a balloon weight and attach the other end to one of the balloon clusters. Add the other three clusters below the first one. The end result is 16 balloons of the same color on one ribbon. Repeat with all the balloon colors.
Step 2: Make the arch
Arrange the balloon clusters in the order in which they will make the arch. Cut the weight off the second cluster and tie it to the top of the first. Continue in this manner with the first four clusters to make a column. Repeat for the other side. Attach the two columns together in the center to form the balloon arch.