The materials are all the usual suspects:
-Masonite/MDF baseboard (usually 3/8" or 1/2", but for this smaller hill, just 1/4").
-1" thick high-quality insulation foam for the base contour.
-rubber cement to glue the base contour down to the baseboard.
-lots and lots of WOODCHIPS.
-Hot glue gun and lots and lots of GLUE STICKS to very quickly and efficiently glue the woodchips to the styrofoam, and to each other.
-various pieces of styrofoam cut to size and shape to form the interior of the second contour, inside the ring of woodchips. As you can see from the pictures, this process is much more an "art" than a "science" (though obviously it doesn't qualify as either, hopefully you get my meaning!).
The "fabrication" of these hills is rather labor-intensive, and somewhat time-consuming, but in addition to IMHO looking good, the end product is both light and highly resilient, able to withstand the rigors of gaming while retaining its looks. So for me at least, its worth the time.
The hill pictured here is my 4th one done in this exact same style -- got one large, one medium, and this second small one. I have the baseboard and base foam contour cut out for a fifth, extra-large, one, which I hope to get around to completing in time for the 133rd anniversary of the Battle of Charasiab, this coming October 6th. I hope to get a game of the battle going using these hills as the high ground South of Kabul, which General Roberts had to fight his way through.
One last note on building this hill: you will see a couple of different black spraypaints used for the prime/base-coat. This is because I hate using anything but water-based paint on exposed or even semi-exposed foam, since in my experience this always leads to foam being eaten away. Still, spraypaint is so much faster and more efficient as a primer coat for these hills, I am constantly on the lookout for water-based black spraypaints. Most of my experiments in this regard have failed to one degree or another. The paint shown here failed as well, simply because it turned out to have a satin finish, which was just too close to glossy for me to live with. But I took my chances, figuring that having been sealed with a couple of coats of the acrylic black paint, I could risk going over it with a light coat of standard matte black enamel spraypaint. Luckily for me, this worked without leaving any visible damage at all. I have since bought an air-brush, and hope it -- alogng with some flat black acrylic paint -- will prove to be the final solution to this ongoing dilemma of how to start the painting process for these hills without damaging the hill itself!
In case anyone reading this HAS NOT seen the previous post on finishing up the paint job for this hill (which is the FAST and FUN part of the building process!), please click on this handy LINK to get there...