Not two tools you would normally associate with a model railway lol. Using a hammer and chisel, a gouge I guess, to cut out the creek from the MDF. I've then covered it in a running plaster. This will then be painted brown and varnished to represent mud. There are quite a few videos about this layout if you are interested on my budget model railway you tube channel #budgetmodelrailways #modelrailway #modelrailroading #ngauge | Budget Model Railways