This is the straightforward instructional version: build a Chladni plate, then observe the patterns different frequencies produce. It comes from Make:'s Weekend Projects series, so it is structured as a parts list and a sequence of steps rather than as a demonstration with an explanation bolted on.
The design choices are the conservative ones — a speaker or driver, a bolt through the centre of a plate, a tone generator — which is the right starting point. Get that working before spending money on a proper wave driver, and you will know whether your problems are amplitude, coupling or plate flatness.
It is dated in one respect: a phone app or a browser tone generator now replaces most of the signal chain. The mechanical advice still holds, and the centre-mounting method it shows is the one nearly every subsequent DIY video copies.