This is cool! I had a player once who gave me no end of grief with their attempted floating disc shenanigans! 😝
I can certainly see why. I would like to present them not only as creative tools and unspeakable dangers but also as a dungeon features. Imagine your players know about floating disks and then bump into invisible wall in a dungeon. Strong enough impact or a little bit of daylight may let them get into this secure area but what hides there? Or they encounter invisible platforms allowing to get in unusual place - why would these disk were set like this? Do they lead to a trap or something sinister up there? Or maybe it is clever shortcut of some smart magic user?