This is the step by step process I used to design, build, and display my Halloween Haunted House pillars. I made the structure out of 1/2" Insulation foam, and covered the outsides with Brick Scene Setter plastic wrap. Then I capped the tops with more Insulation foam, which I spray painted back.
I cut each 8'x4' sheet of Insulation foam into 12 - 6"x4' strips. Then I glued each side together as shown. I used masking tape to hold each pillar together as the glue dried. It took roughly around 3 days to fully dry. I used a wood glue on the first one, but that glue didn't try near as quick as I needed, so I moved onto Tacky Glue, which worked amazingly well. Once they dried, I used the wood glue to glue each section of the stone scene setter to the foam pillars. The wood glue was tacky enough to keep the plastic wrap on the foam, but slick enough to reposition it as needed before it completely dried. Once those dried, I cut 8.5" squares out of the remaining foam sheets ( I only made 10 pillars, so I had 2 more sheets that were left whole). I spray painted them a flat black. A tip...if you get the spray paint close to the foam, the spray paint will slowly eat into the foam and will make it look more realistic as it dries. Once those were dry, I simply used the same Tacky glue to glue the tops on.
I used 6 pillars inside and 4 outside, which completed the design and created a nice flow of the same theme from outside to inside.
Next year, I will need to add some more weight to each pillar simply because they are too easily moved and tend to fall over when bumped.