I loosely settled on a very upright design roughly 16"L x 10"W x 14 high and cut rectangles of foam to fill out the shape with a hobby knife and steel straight edge.
In keeping with the style of my Goblin Valley terrain, the foam was glued up into blocks for shaping of each type of strata. I glued the foam pieces together with 3M Styrofoam spray adhesive. This sprays out in a relatively thick sort of figure-eight pattern and results in almost no over spray. It is also much faster and/or less hassle, than any other method I know of for gluing foam.
Next stage was to begin shaping the foam. I drew a 2 inch square grid on the top layer of foam to transfer the basic design shape onto the foam, then rough cut the profile with a hack saw blade. I decided to rough out the shape, using a surform tool and my old metal sanding sticks.
I now came back to the second layer and began shaping it. This layer took some time to shape, as it involved the most detail. Rough removal of foam was done with the surform tool, while finer removal was completed with the sanding sticks. Additionally, crevices were cut into the layers using an older Foam Factory "pen".
As I was shaping the second layer, I started to consider if the standing height of the Mesa was too upright for the table top. I decided for the time being to continue the detailing of the second layer, and let the piece take a little more shape, but was considering removing as much as three inches of foam layers from the second and third layers.
Shaping the third layer mostly involved using curved sanding sticks and the Foam Factory stylus/pen to add a little more texture to it's contrasting shape.
The last or bottom layer was essentially a sloped "moat" of eroded and pulverized rubble that had fallen from the mesa over the centuries. This was mostly shaped with the hacksaw blade and surform tool.
Once the general shaping of the layers was complete, it was time to clean up and add extra details to the layers. This was accomplished with a little bit of milling with a Dremel, and a lot of sanding with 150-180 grit paper (and small orbital sander where possible), and a coarse Squadron sanding stick. I added a little more crevice detail with the Foam Factory tool, and cleaned it up with a little sanding.
The last stage of foam-work was to create the rocky "goblins" for the top of the formation. These were cut from scraps of foam, and shaped with the various tools described above.
The top layer was conceived to be favorable for a defensible position or residence for a small group or even single individual. So the rock formations were shaped with this in mind. Joints in the foam, divots, and other blemishes were filled with one-step or light weight spackle.
Once all of the remaining stone work was shaped, it was time to prime and paint. Primer is more of just adding a protective layer to the foam, using a thick artists acrylic paste; it this case from Golden. Then paint with artists acrylic colors to match my old terrain pieces. The color ended up a touch off, but there is 14 years between the first pieces and the last, so I'm not too unhappy with the results.
Below you can see each of the modules separated from one another. This allows some variation in how the terrain can be used on the tabletop, as well as, a little more ease of handling for storage.
Below you can see two of the new pieces flanking one of the original goblin valley pieces. Despite the differences in the paint, the final products are very similar.
Part 2 of the Mesa will deal with the post-apocalypse residence and adaptations to the mesa.