A method of making an interferometric modulator element includes forming at least two posts, such as posts formed from spin-on glass, on a substrate. In alternate embodiments, the posts may be formed after certain layers of the modulator element have been deposited on the substrate. An interferometric modulator element includes at least two spin-on glass support posts located on the substrate. In alternate embodiments, the support posts may be located over certain layers of the modulator element, rather than on the substrate. A method of making an interferometric modulator element includes forming a rigid cap over a support post. An interferometric modulator element includes support posts having rigid cap members.