I've never done a tutorial of any sort so I hope this goes well. My bunker method is pretty similar to Doron's, and probably everyone's I suppose. Here's an example of a greenside bunker:
1. After dropping my fringe shape I draw in my bunker(s). I use the distance of the approach and angle into the green to figure out how deep I want it and the size and shape. Longer irons will warrant a simpler, shallow bunker, usually to the sides or back of the green. Short irons will typically have to carry a bunker that's small or complex in shape and fairly deep.
2. I then drop the sand texture followed by a large default texture to encompass the entire greensite. I will work all my greensite elevations within this texture.
3. After working most of my green elevations I now start on the bunker(s). I first start by drawing simple shapes around the perimeter to create some mounding. Then I'll raise these with the hill tool 2-5ft. I'll then draw a large shape around the bunker and smooth 4-5 times on the third setting.
4. Next, I right-click -> use as a shape on the bunker and inflate 2-3 feet, depending on the size of the bunker. Then flatten to minimum height.
5. I delete the shape I just flattened and draw a large shape around the bunker. I'll then smooth once on the 4th setting and delete the shape.
6. Now I'll use the bunker as a shape again and deflate it 3ft. I'll then draw a shape around the bunker, following the form of the bunker and about 10-20 feet larger. In the past I would just inflate the bunker shape, but I find this new way to look more natural and not so "perfect".
7. I'll then use the hill tool to drop the two shapes 1.5-3ft and delete the shapes.
8. Now I zoom in and draw a shape inside the bunker to reflect the lowest part. I don't pay much attention to how good this shape follows the shape of the bunker, as there is nothing perfect in nature. Then I'll use the bunker as a shape, so I have two shapes selected.
9. I then drop the two shapes with the bunker tool about 1ft. Then I delete the shapes.
10. Next, I draw a large shape around the bunker and smooth 2-3 times on the third setting and then a bunch of times on the second setting. Then I delete the shape.
I may draw some shapes in at this point around any surrounding areas that need more smoothing, but I won't smooth the actual bunker anymore.
11. Next, I use the bunker as a shape and inflate it 3 inches, change it to my lip texture, and drop it. Then I'll select the bunker texture, duplicate it, and inflate it 3 inches. I then Ctrl-click the bunker shape to have both shapes selected.
12. I then drop the two shapes using the slope tool to between 0.12 and 0.175ft. I always stay in this range because I think it looks more realistic.
13. The last step is to optimize. I optimize the bunker texture on the third setting and the lip texture on the eighth setting. I also optimize my large default texture after each bunker on the second setting.
After my bunkers are complete I move on to finish the green contours. It takes me about 10 min to do each bunker. I hope you could follow along!!