Pastiche

I like the word pastiche (pas-teesh) because it is one of those words that can be either a noun (thing) or a verb (action). What it means is also that way. It means copy, as in a copy of or to copy another's artistic style. 

If someone at school paints a picture in the same style as you, you could tell the teacher they pastiched your art or their work is a pastiche of your art. 

However, you should know, that many famous artists tried their hand at copying the styles of others. Among them are Vincent Van Gogh and Grant Wood. Also, remember that imitation is the greatest form of flattery. If someone is copying your style, it is probably because they admire it. Tell them to pastiche away!

Johannes Vermeer's "Girl with a Pearl Earring" and a pastiche of the same.