I wrote these ideas in my black book years ago and wanted to share them with you as I am not going to use them.
This idea is posted elsewhere on this forum (see my profile under postings). 3D ping pong mobile. Since most haunts have restrictions with ceilings this idea will not be practical for you. But if inside your 3d attraction there is no height restrictions, this would look great. The mobile is made of many ping pongs colored in 3d paints. They are attached with black thread and tied to the wires that make up the mobile. I know using thread is bad idea, but this mobile needs to hang out of hands reach. Google, ‘mobiles’ to see what’s possible to make. I suggest using the ping pong balls because even if someone could jump up to grab it, the balls are too small and light to get them every time.

This second idea uses foam nuts.
Picture a hallway about 12 feet (or longer). There are fans under the grid floor. There are slower fans on the walls (also grids/holes). At the end is hanging fabric with 3d painted dots on it. Hundreds of foam nuts/noodles are painted in random 3d colors. Turn the fans on (adjust speeds to make sure the nuts only lift 8 feet or so). The wall fans only need to make sure the nuts rotate and keep off the walls. Throw in the nuts and walk through. Adjust the nuts for the right 3D effect (too many will not work and just look like a blur).

Each of these ideas have problems that restrict haunters from using them. The foam nuts, for instance, will make a huge mess, especially if the nuts are taken by people and carried around. Plus I have not tested either of these ideas, so if you’re interested in making them please test the idea first.