It's clear that the design for the ice cream cones was made before they started the bulletin board. See how they used the same picture as a border for the whole thing? I bet that they projected the image up on the white paper background and traced the outlines that they wanted. They might have free-handed the ice cream cones, but I think it would be easier to project and trace. However they did it, they had some idea before they started adding the tissue paper. In fact, you can see some of the pencil lines of the outline from where they traced.
I tried to get some close up shots to show off the detail of how the creator bunched up the tissue paper and collected it so that it made this awesome scrunched up effect. They really just crumpled it up and stapled the heck out of it. When you step back and take a look from far away it gives a really awesome effect and makes the ice cream really pop out at you. I love how they added the pictures on the right to get people's attention and keep their interest AFTER they looked at the cool ice cream cones. What's more social than an ice cream social? Pictures of the people who were being social at the social! Nice finishing touch. Whoever did it, great job and great inspiration for next year!