Hi Trainman2001,
I built 3 of this type of mountain with contours. I had to have them portable or removable. I made horizontal supports out of 1" x 1" that I ripped. I then put a block at the top below the peak. I drilled a pilot and installed a screw eye that could be used to lift the mountain. The screw eye can then be taken out when installed.
I first tried aluminum window screen and pinched it to shape and stapled it to the contours. I then painted (brushed on) a thinned mix of drywall spackle. it didn't fill the holes that well. I should have used plaster. Then I painted it.
The second try is a two piece assembly to hide the electric panel for house. I have a 44" tunnel base with contours about 46" high. Same construction and aluminum screen. Only this time I tried a Dave Frary tip that he used on a museum layout. I covered all of the pieces with Great Stuff foam used for sealing cracks and such around the home. It expands and becomes rigid creating a relatively lightweight shell.
This method worked great until it time to carve it. The stuff is hard. I used everything I could find. The best tool turned out to be electric carving knives. It was slow and painstaking for an almost 4' x 4' structure. I gave up and didn't finish it. But, the concept works.
Then, I discovered a thread where a member had used a 4" angle grinder with a metal cutting disk. I ha to access the panel and tested the grinder while it was off of the layout. Bingo! Use the grinder for rough shaping and whatever else you have for detailing.
I tested a few chunks that I cutoff with the standard artist acrylic coloring method. I left any air holes and such. The black was for the first coat needs to a little thicker then when working on plaster. The dry brushing the colors it works the same.
I'll add some photos later of my learning experiences.
This method is fast. This method does make the land form removable and portable. Now that know how to attack the foam, I like it much better.
Oh, the first mountain never progressed past framing. I haven't built that layout yet. Long story...
