first run at elevation change to 6 1/2" used scrap packing for the elevation change, it came from lowes and was used to hold up a new refrigerator.. and then i used the woodland scenics plaster paper and some old fashioned starch where the track will sit, i used 1/4" cardboard under the track to make it quieter, it worked on my other layout, and it is cheap, also have two woodland scenic rock molds and associated casting plaster
but have a mountain literally to create and do,, figure this is maybe 10%, but i think i figured it out and i made a whole box of "rocks" to use when i get some more plaster to put it them up
regards
oh yeah i added sort of a backdrop