Here is a method to modify resources nods model so that you can see them easier. For example, I changed all herbs to a very shiny picture so that I can spot them very very easely and farm faster. Same thing could be done for mines, chests, anything basically.

1- Download MyWarcraftStudio at http://www.curse-gaming.com/mod.php?addid=657
2- Open MyWarcraftStudio(MWS) and go into the File menu, and choose Open MPQ archive
3- Browse to the Data folder inside your WoW directory and open model.mpq

We will take for example Firebloom herbs

4- Browse around to find the Firebloom model. You will find it under World/SkillActivated/TradeskillNodes/Bush_Firebloom.m2

As you can see, this is a m2 file. You can replace this by any other m2 file.

5- So, choose a model you want to replace the Firebloom with. Let's take a treasure chest as an example. You will find the treasure chest under World/SkillActivated/Containers/TreasureChest01.m2

6- Right click the treasure chest file and choose Extract File To... and save it on your desktop.

7. Now close MyWarcraftStudio

8. Open your WoW directory and browse to the Data folder.

9. Now create a directory tree that has the exact same path as your firebloom model. For our example, you will create a directree tree that would be : World/SkillActivated/TradeskillNodes/
Careful! It's case sensitive. The directory World is within your Data folder. So it would be:
Wow directory\Data\World\SkillActivated...ect.

10. In the deepest folder (in our case, TradeskillNodes), copy the m2 file you saved on your desktop (the treasure chest file in our case).

11. Rename that copied file to the exact same name as the firebloom file (in out case, Bush_Firebloom.m2)

12. Restart WoW

13. Enjoy your firebloom that looks like chests! Obviously, if you know how to create mpq files, you could make your very own images and replace any mpq file with it!