“That no money shall ever be taken from the public treasury, directly or indirectly, in aid of any church, sect or denomination of religion, or in aid of any priest, preacher, minister or teacher thereof, as such; and that no preference shall be given to nor any discrimination made against any church, sect or creed of religion, or any form of religious faith or worship.” Missouri Const. Art. I, § 7.
“Neither the general assembly, nor any county, city, town, township, school district or other municipal corporation, shall ever make an appropriation or pay from any public fund whatever, anything in aid of any religious creed, church or sectarian purpose, or to help to support or sustain any private or public school, academy, seminary, college, university, or other institution of learning controlled by any religious creed, church or sectarian denomination whatever; nor shall any grant or donation of personal property or real estate ever be made by the state, or any county, city, town, or other municipal corporation, for any religious creed, church, or sectarian purpose whatever.” Missouri Const. Art. IX, § 8.Now, as that is written, I don't see anything in the US Constitution that would prevent Missouri from implementing that as written or repealing it. The equal protection appeals to the Fourteenth Amendment seem to be a bit of a stretch because it does not unduly "abridge the privileges" of citizens that they might not be able to realize through other means. And it's perfectly sound on the Establishment Clause -- it's the Establishment Clause on steroids.
Now, that all said, that doesn't mean that just because I think Blaine amendments are Constitutional, that I think they're a good idea. If a private, secular school can get a grant for ground up tires for their playground, it seems that Trinity Lutheran and Darth Vader's Home for Wayward Sith should be able to get a grant for ground up tires, too. The absolute proscription of public funds falling into the hands of religious organizations through programs that are more generally available, is, in my opinion, foolish and short-sighted. The Establishment Clause does not proscribe government at any level working with religious organizations to further public goals.
The answer to the problem of Blaine amendments is not to have the Court say it hurts their feelings and makes them feel bad and because it was born of anti-Catholic sentiment or whatever, that people can feel free to ignore it, or strike it down because they don't like it. It's bad law. Repeal it, Missouri. And all the rest of the states who have them, too.