The Fill Square with Stone was one of the easiest items to construct. I simply shaped a rough cube of blue Styrofoam to fill a game square, coated it with white glue, covered it with sand, and then painted it black with a dry brush of gray.
The Fill Square with Slime took a little more work. I first made a clay version of it. Then a mold of the clay. Then filled the mold with clear resin tinted with green ink. This is my first attempt at casting and mold making. Not bad, but it has a lot of air bubbles. Better instructions can be found here.
The Safe is a box of plastic card covered with green stuff and painted silver with a black wash. The bottom is open so it can cover items like treasure chests.
The Pit is just a square of floor tiles around a card stock base painted black. The Thorn bush and Rosebush are model railroading lichen soaked in a white glue and water mixture to make them stiff and mounted on a clear acrylic base. The rosebush has painted spots to indicate roses.
On an attached note - registration for this years Origins events has gone online. My 3D Wiz War game will be run on June 25th at 3:00 and on the 27th at 10:00 A.M. It is under the tabletop section of events.