My god child and her family have one toy that is a tube knitting machine. It is made from plastic and as that it is prone to break. In fact, one part broke but her mother succeeded replacing it herself even though it was rather hard to get that done. But all in all most of us are rather crafty ; )
To keep my blue cold freezing under-circulated stump warm, as that reduces stump pain and phantom pain, a tube knitting option isn't necessarily bad to have so I figured y'all might want to have a look.
That however is just a toy.
To get the real deal, google for Addi Express.