There are many different techniques for creating landscapes. I found this one the other day and wanted to share it. It's from a YouTube channel called Scale Model Trains & Colorado's Joint Line. It uses a combination of extruded foam (rigid foam insulation) with a sheet of blanket batting for creating hills. I really like the texture that it creates after you paint it.
Check it out: https://www.youtube.com/watch?v=9C6aHEoUWYg.
I also have included a follow-up video that shows how well this technique can take details. It really looks fantastic!
Have a looky: https://www.youtube.com/watch?v=vvM1XyxC8Bs.
I plan on posting more to show other techniques.