Here is the scenario map for Spencer’ Ordinary from British Grenadier scenario book #2.
To make the “lumps and bumps” I use pieces of wood and coir doormats (whole mats and chopped-up pieces). Try to build up several layers for each hill.
These are then covered with hanging-basket liner bought online from gardening suppliers.
I then place a few commercial wargame hills to round off some of the crests. These could go under the liner, it makes little difference but the hills pick up less fluff this way.
The whole thing is then covered with a couple of cloths. These are felt, but use any sort of blanket. Heavier tends to be better.
The final cloth layer is my sprayed fleece fabric. Spend a bit of time pushing the cloth layers down between the hills rather than being pulled taught between them.
Next I add roads, streams, fields and buildings. Then comes fences. I’m only approximating the map here. To be closer would need me to extend the table to 8x6. I use duct tape to join the road sections together.
Now I add trees, patches of long grass and rocks to break up the plain areas. Here are a few shots of the completed battlefield. I’ll now leave this overnight for the cloth to settle down. The photos still don’t fully show the effect of the hills but you should get an idea.