I plan to connect these platforms with bridges, and block off access to the bridges with the little wormholes you see below that serve to hinder your progress. Interacting with the crystal toggles its color between red and blue and deactivates wormholes of the respective color while re-activating wormholes of the opposing color. I've found several working layouts for this, but none that I was completely satisfied with. If anybody can think of a way I should place the bridges (or even adjust the platforms, if necessary) I'd appreciate you sharing it with me.
Edit: If more than one crystal is needed, I don't mind at all.
Sauce:
Thanks!