This table was built to support 4' by 6' insulation board sheets. 3/4" or 1" thickness was perfectly fine for home use. The insulation board is not tough enough for the retail store. I made a hardboard and plywood board to fit. You can see the insulation board is still on the bottom support.
I use the same methods to finish MDF, plywood, hardboard and insulation foam.
Drywall mud/filler
latex paint
Blended craft paint colors. The rock surface is pine bark
Woodland Scenic Flocking and Mod Podge for water
You can see a 3/4" by 4' by 8' Pink insulation board in the background. That size board would need to be framed. However you can purchase it in 2' by 2' sheets that are rigid enough and modular enough for the kitchen table.
2" thick insulation foam is also available.
I like to use the thicker sheets of insulation foam for mountains
White beaded foam or Styrofoam requires a base of cardboard or MDF and
foam coat
See this link
http://hotwirefoamfactory.com/Foam-Coat-Foam-Glue-Foam/https://www.youtube.com/watch?v=rpbOzjnAueI