I have made many sts of yoga mat terrain and am currently making more. Here are some things I have learned:
1) Always use wood glue for everything. If you use white glue, it can pull while drying and disrtort the mat.
2) Glue carpet or felt to the bottom of the mats, not chipboard. It keeps the terrain light and the felt helps to grip the table.
We get slapped around, but we have a good time!