I find this all pretty intriguing as well. The wire is supposed to collect energy from the atmosphere and direct it to the plants, stimulating every part of its growth. There's quite an extensive bit of literature on the internet about it and the general consensus seems to be that it's very effective for boosting growth.

The filament is PLA and the cones are generally intended as just a shaper. If you have some solid thick copper wire it will hold the shape this would work best, but speaker wire it probably won't work unless completely stripping the wire casing, which is a pretty nightmare endeavor with multi strand general purpose wire. They don't get hot enough to melt in the tents but outdoors might be a different story.

I've never tried PETG in the few years I've been 3D printing, only the PLA. Maybe I'll give that a try though. It would be nice to have a material with a higher melting point.

These shapers are on thingiverse. I meant to put this in the post but must have been high and forgot: https://www.thingiverse.com/thing:5960175