Weightmaps
Weightmaps are used in this tutorial to act like a paintbrush for your procedural textures. We can create a weightmap to dictate where a procedural texture should or should not appear.
Firstly we'll make a weightmap called "Smooth". This will be used to mark exposed areas on the object surface where it has been worn away and the surface is less rough. To create a weightmap, click on the "Map" tab at the top and go to "New Weight Map" on the left menu bar. Enter the name "Smooth" and set the initial value to 0%.
Using point selection mode, select all the points that are on the edges of the surface that protrude significantly (see image below). On the same menu bar, click "Set Map Value", select the "Smooth" weightmap in the drop down box, and enter 100% for "Value1".
Now press "z" to use the weightmap airbrush, press "n" to bring up the settings, and make sure you have the Weight Value set to 100%. Adjust the radius and strength to your liking, and use the airbrush to paint on other areas that you feel should be worn down and smoothed. Note that you will need to select the "Smooth" weightmap in the drop down list at the bottom right of the screen (making sure that the "W" is selected and not T or M), and set the viewport to "Weight Shade" to be able to see the effect you are having.
Once you have finished, create another weight map called "Dents" (with initial value of 0%) and use the airbrush again, but this time painting areas that should be dented or damaged.
You can see here why I decided to subdivide those particular parts of the mesh.
That's all you need to do in modeller. The next stage is the surfacing in Layout. If you want to download the model at this stage of the tutorial (i.e. without surfacing), use the link below.
