Popular television shows feature artists designing everything from new clothes to delicious food dishes.
Why don't use "who design" in the sentence?
This construction, a gerund clause†, has quite a different sense than a relative clause.
In the sentence “Popular television shows highlight artists who design everything ...”, the object of the verb highlight is artists:
What you are shown is people—artists—and the relative clause adds information about what kind of people you see.
In the sentence “Popular television shows highlight artists designing everything ... ”, the object of the verb is the entire clause which follows:
What you are shown is not people, but actions—people-doing-stuff.
The verb design is cast into the -ing form so the clause may act like a noun and serve as a direct object; but otherwise it is an ordinary sentence. Grammarians call this a subordinate or embedded clause, because it is “lower than” or “stuck inside” something bigger.
† Gerund is the traditional name for an English -ing form which acts as a noun. When it acts as an adjective, or as a component of a progressive construction, it is called a participle. The important thing to keep in mind is that in both cases it also acts as a verb. That is the origin of the name participle: it is something which “participates” in the qualities of two different word classes.