Although I currently play Skaven and Dwarves from Fantasy and Space Wolves from 40K I did at one time collect, paint, and convert other models from other races. Here are some of my earlier models.
Necrons were by far one of the easiest models to convert and paint because of their interchangeable arms. As you can see from the pictures.
I took the arms from a Wraith and placed them onto a Lord to turn him into a Flayed One and then took the Weapons and Resurrection Orb from the Lord and gave them to the Wraith
The legs that i gave my Destroyer I took off of an old Tomb Spyder and placed them in the vents on the side of his body