The past tense of make a mountain out of a molehill is made a mountain out of a molehill.
The third-person singular simple present indicative form of make a mountain out of a molehill is makes mountains out of molehills.
The present participle of make a mountain out of a molehill is making a mountain out of a molehill.
The past participle of make a mountain out of a molehill is made a mountain out of a molehill.