Here is a helpful link to an Army Terrain Model Kit for the platoon level for sale on Ebay. This would make an excellent ROTC Advanced Camp Terrain Model Kit. In addition, if you message the creator, he will custom creates pieces/colors etc for your particular wants or needs.
I have found this Army platoon terrain model kit to be cheap ($29.99), durable (laminated and taped with pennies), and useful. The reason this TMK was most helpful for advanced camp at Fort Knox was how fast it was to make a professional looking visual. I briefed multiple missions using this kit to my SLs or squad; in addition, multiple other cadets requested to use it!