Honestly that just looks to me like some sort of plastic for height with a base for the pots to stand on and a bit of felt for wicking up the nutrients. Since she has an overflow system, the height of the water is always the same and nothing has to really "float" for any kind of valid reason.
Just has to let the water flow through/under it and be rigid enough to take the weight of the plants.
https://mingodesign.com/services/
This is the company who custom made the wall, you might be able to ask them. But imo those just look like some plastic structural thing they cut up just to act as a spacer (that thing doesn't look like it floats).
Honestly that just looks to me like some sort of plastic for height with a base for the pots to stand on and a bit of felt for wicking up the nutrients. Since she has an overflow system, the height of the water is always the same and nothing has to really "float" for any kind of valid reason. Just has to let the water flow through/under it and be rigid enough to take the weight of the plants.
https://mingodesign.com/services/ This is the company who custom made the wall, you might be able to ask them. But imo those just look like some plastic structural thing they cut up just to act as a spacer (that thing doesn't look like it floats).