The system for constructing nifty widgets, magic weapons, servitors, horses and everything else has its own section.
You will find those rules on the Items Page.
Items bought with Character Points become virtually indestructible. Even if the Pattern and the Logrus team up and eat the item, you will eventually be able to either duplicate it or get it back. Only your death can lead to its permanent destruction. It is possible to have it stolen, though.
You can have lots of stuff not paid for with points, subject to GM approval. Such items will tend to be ephemeral in one's life, however. Still, it's easy for Amberites to get money and buy nifty toys.