I'm trying to recreate this texture on blender for 3d printing however I am having difficulty achieving the raised parts of the hollows.The below image is the closest I am getting. Any tips?
You can use the Tissue add-on for this.
Create a quad mesh with the contours you want, then create a tile object that is a pit.
Select the tile object, then the contour object and press the Tessellate button. A new mesh will created with your perfect pits where each quad face was.
You'll want to keep the Scale value low, and enable the Merge option so each tile will be connected.
You can then smooth the shading and add a SubSurf modifier to get something very close to your reference photo.
Just like Mr Zac said you should add more resolution with a subsurf modifier and then add a displacement modifier and find an image texture to use as the displacement value. the image needs to have highs and lows in the correct places in order to get the effect you want. if what you need is so specific then you might need to create a custom image.
EDIT: if you don't understand how to setup textures for displacement ask and i can help.