I took an art class once that taught me something that I just had to spend 5 minutes googling to really remember again. There was an artist named Sol LeWitt who, to quote the wiki… “he transformed the idea and practice of drawing and changed the relationship between an idea and the art it produces. LeWitt’s art is not about the singular hand of the artist; it is the ideas behind the works that surpass each work itself.”
The thing about him that I took away from the class is that he didn’t create a lot of his sculpture, he simply defined it in terms of math/measurements. Some sculptures were created that way as unique commissioned works, but others he considered the definition to be the art, and if anyone wanted to make their own sculpture based on his definition, he was OK with that, because it wasn’t the physical sculpture that was art, it was the idea behind it. Since the class was at Ohio State, we were all familiar with one of his works, which he designed at the University’s request but didn’t actually build himself:
It’s my understanding that anyone who goes out and gets white blocks of stone in that size and arranges them in that manner can claim to have a LeWitt sculpture, even though he’s dead.
Of course, many large sculptures necessarily require teams of people with an artist simply directing the activities. Architects may consider themselves to be artists in that regard. In that vein, movie/stage directors, composers, conductors, etc etc etc.
There was also a guy that I don’t want to google about right now who was a proponent of the idea of “found art.” That is, some rusty artifact in a field somewhere is just a rusty artifact, but bring it into a studio and it’s art. No effort required aside from vision. From what I’ve seen, a lot of modern sculpture involves “found” objects like this. edit: Found object - Wikipedia
But if you’re talking about conventional art-that-hangs-on-walls, I’d imagine that Warhol’s simpler silkscreens can be pretty easily recreated by someone with silkscreen experience but very little artistic talent. And Lichtenstein’s comic book style paintings probably wouldn’t be very technically challenging, especially with a paint-by-numbers approach.
Anyway, that’s everything I know about art.