how to make a mold of this part ,
Try following this tutorial and applying it to your part.
Let me know if you have any problems after that.
Here it is (excuse me for my bad english)
Answered with a tutorial: https://grabcad.com/tutorials/how-to-make-a-mold-of-this-part
To make a mold, you can create a parallelepiped round this part and then you can use "Combine" command: http://help.solidworks.com/2012/English/SolidWorks/sldworks/HIDD_DVE_FEAT_COMBINE_BODIES.htm
Then, you can divide it