blender roughening effect

when creating the second model for my 3D project i learnt a way to roughen surfaces on blender for more texture. when in edit mode (tab key), make sure you are in vertex mode and also on the right from that u will see a little grey circle (proportional editing) and select enable then next to it another little window will come up. select random from there. making sure that u have multiple vertices (this can be done by loop cutting) press 'B' to create a loop to select multiple vertices at once. when selected press 'G' (grab) to raise to make a roughen effect. make sure you don't over do it other wise it will be just a mess.

here's an example that i have done with my project.