This is my crystal ball, which is used for scrying. After entering a meditative state of mind, it is possible to see events happening inside it. The trick is to keep your mind open and allow the thoughts to come to you, rather than trying too hard to see things for yourself.
In years gone by, witches used whatever came to hand. Therefore a witch who lived by the sea would be most likely to use a fisherman's float as a scrying tool because that is what she had available.
Nowadays we decorate our Christmas trees with balls of many colours, but many people forget that these were originally pagan tools, as was the custom of bringing in a small tree at Yule-time.
You too can use whatever is to hand. All you have to do is remember to bless it and charge it during a waxing moon. Keep your ball in a safe place and keep it clean.
If you can afford it, you can purchase a real crystal ball. There are many available to buy on the internet or in crystal shops. It should be regularly cleaned and kept safe and provided you do these things, it will bring you many years of fulfillment.