I needed a good scare and a way to pass out the candy. Rather than do a drop panel, I thought it would be fun to have some demon actually crash through the walls.
I had some 2-part flexible foam that I had used the previous year to make the fake spikes, so I thought I could use that to make fake rocks that were safe to crash inward at the kids. So, I made latex molds of some rocks and boulders I had in my front yard and made some good-looking fake rocks.
Since these rocks were going to look like they were embedded into the walls, I cut them in half so that one side was flat. I then got strips of elastic bands from a fabric shop and sewed the rocks to the bands in vertical strips like shown below.
I then cut a hole in my foam-board wall and placed the rocks over the hole, attaching them to the wall with the elastic.
The rocks did not fit perfectly together but the gaps let the actor see the kids approach while he was well hidden. I draped some black cloth down on the backside of the hole so that the area behind the rocks with the actor was very dark. That was it. Here is what it looked like (with the lights on) as you approached.
All done. I imagine it would be simple enough to cut up some foam cushions for the rocks as it is tough to get cheap flexible foam these days.