In order to make FLAG experimentation accessible to people without 3D printers, I developed the design that was submitted for the 2021 Hackaday Prize. It can be made with only a sharp knife, plastic film, conductive tape, and 3 suitable diodes. If you have a Cricut cutting machine or know somebody with one, it will be a much quicker way to cut out the pieces and links to the Cricut files are provided in the instructions. The simplified design has a downside in that it can put repeated bending stress on the diodes, and the leads on some diodes will occasionally break. I'm sure somebody will come up with a better way to mount the diodes that will still not require the 3D printed parts.
The Hackaday Prize FLAG design has been tested outside in humid conditions:
And this design has even mounted to my truck antenna to go for a drive, with a little bit of foam to make sure it wouldn't short out on the antenna: