Como dizer "desenhista" (no sentido mais rústico) em inglês

Para o que se deseja, DRAWER é o mais indicado.

And also:
"sketch artist" would be someone able to draw a person (usually working with the police or courts).
In general ways, we could answer your question by saying that is a person good at drawing.
There are also illustrators, artists that draw faces, some are so good that you would describe somebody else and they are able do a sketch, or do a pretty close drawing.

Drawer? People rarely say that in this context because it's mostly associated with the thing in which one keeps their clothes haha. Even if the context makes it clear it still sounds weird so people usually say "drawing artist". It also depends on the specific type of artist. There are sketch artists as pointed out and described by Paulo and realist artists (these are very talented and pull off a very close life-like representation of whatever or whoever it's based on), among others... But the general and most common term is "drawing artist".

Designer decorator, display artist, displayman, landscaper.