Tools of a professional painter - brushes, paints, pencil. With them, he earns his living, since it is problematic to do this with "pure creativity", you need to invest money and time in "creativity", with unknown results of their payback.
Therefore, most artists (including the great ones) have never been against earning extra by painting "to order"
Copies of famous paintings are also in demand, such "orders" are paid especially well, since copies are mainly used to decorate expensive apartments or mansions. There are, of course, orders from museums and art galleries, but this is a separate issue.
Often, copies have to be made from photographs, which complicates the work, after all, a photo is a flat image that does not give a complete picture of the master’s technique, the play of light and other nuances.
So do not judge strictly, here is my copy of one of my favorite paintings. I did it "for the soul" and to practice copying techniques, but, in the end, I successfully realized it in a private collection.
Eugen de Blaas The Flirtation
"Create, invent, try" 
