not sure how much it costs, but the luna stocking stuffer certainly works. Pretty sure they have someone else build them.
using a ram to pack socks works best if you’ve got the sock supported. as @Indianajones420 mentions, PVC works and is cheap…sometimes you can even find it just lying around…eg Tube socks cause shocks? (So don’t do it!)
@Roguelab has suggested a metric stainless tube rather than a sock. Tricks of the trade - #25 by Roguelab . Luna has stainless baskets for their socks, but I don’t know if anyone actually uses them…
the real trick is actually getting the size of your socks right. too big and they won’t go in the tube. just a hair small, and you can pack more material and still get them in the tube.