As
@DDave said, hardware stores, or in the meantime just use bluetac
and if you would like it to be able to slide around a bit (not sure why) but you could use those little felt feet that you get from $2 stores to put on the bottom of chair-legs. That'd atleast give it some elevation so that the fan still works. Rubber will be best though
If you are referring to the photo I posted a few pages ago, I'm not 100% sure if I had the standard Arizer whip in the photo or if I photographed the SSV tube but regardless, they look the same apart for a few small differences. The SSV one is not rigid whatsoever. If the Arizer whip is a 1/10 in flexibility, the SSV one is a 10/10. Doesn't drag or pull and will never snap back to its origional shape and go flying around your desk. It's soft, smells like nothing at all and generally feels good. It's easier to store as well, because you can wrap it in a circle and then weave it through itself to get it into a very small shape.
Fuck it; ill post a photo comparison for you. if you are going to buy it, get the LARGEST size from their store. It's cheaper that way, and then you can cut off lengths yourself as you require them and save on shipping cost later on when you need more whip.
Here is a pic of the two next to eachother. (SSV whip on the left, Arizer on the right)
Closeup, sexy whip. These are just webcam photos. If you want a comparison of the two whips with my digital microscope or a better quality camera just let me know, but take my word for it; well worth buying! Get some other stuff at the SSV store while you are at it so that you aren't just paying postage for a few lengths of tube though! The SSV elbow joints are top quality also as mentioned in this thread by a lot of people