mini 1 1/4" metal springy (aka slinky) - what on earth can you use these for?

I discovered I had two of these mini slinky coils.

They are 1 1/4" (c33mm) diameter and XYL had just finished BOTH the tin foil and the cling film so I had a pair of identical cardboard tubes.

A quick test and I can slide the tubes inside the mini-slinky and stretch it out and connect to it along the length (about 12"/300mm). You cannot actually solder to it but you can wind wire about it and solder that in place.

So I am going to make a couple of multi tap inductors for antenna experiments..