Ok here are a few ideas in response to alternative materials to the lace.
First of all Michele suggested fiber glass or acrylic. I am not sure about the acrylic but I believe the fiber glass could deteriorate with the sun and may be difficult to cut patterns out of it. Moreover, I think it would be very difficult to make this material look nice as it would probably have to be painted.
In my opinion a material such as wood would be the most eco friendly and nice looking. Similar to how wine barrels are mad we could make a long barrel of wood. We could easily print the patterns out and transfer them to the wood to cut with a router.
Another idea I was thinking was using copper. Copper can be bought in thin sheets and I believe would acquire an interesting patina over time.
In regards to the felt used in’s projects I am almost sure it is part of his own patented invention. However I am wondering how hard it could be to make a substitute. According to Blank’s website all you need to grow plants is water, soil is only something for the roots to attach to and retain water.