How do I paperclip train when not using soil or media?

Using nuts or other weights at the ends of paperclips just resting on the lid of a hydro tub wasn't getting the job done, and even when you use media, that's a pretty narrow radius in which to try to stick paperclips, with or without weights.

The answer I found was to use small eyehooks (the kind that look like a question mark except that the question mark is a closed circle) as anchors for the paperclips. Screw the small eyehooks in a circular pattern around your netpot, or, in the case of not using media at all, around the hole used for the plant's stem.

The circle of eyehooks (you can use 6 or 8 to get started) serves as a good start.
Note that you can use these eyehooks not only to secure paperclips, but to secure twine used during training through veg and 12/12.

Nute changes are easier since when you lift off the lid, the eyehooks provide extra support for the plant.

Further, you can always screw in another eyehook exactly where you want to put a paperclip or to tie off a new piece of twine at just the right angle.

Finally, in the case of hydro grows without media, you can also screw in the eyehooks from the bottom of the lid to help provide more support for netbags you might use to hold the roots of each plant in the tub.