Internally-etched crystal balls (and other shapes) are everywhere here. You can find them in temple (Buddhist and Daoist both) souvenir shops, in souvenir shops in general for those not in ball form (for some reason crystal balls are used only in 风水(fēng shui)/religious contexts, less commonly as souvenir decorations) and they come in sizes ranging from 30cm+ (which are HORRENDOUSLY expensive!), down to 4cm or less.
I shared a pic recently of a 10cm crystal ball with Buddhist iconography in it, and here now are two 4cm crystal balls (again with Buddhist iconography).
Now here's a dirty little secret. Small crystal balls (10cm or less) are DIRT CHEAP. The 10cm ball I shared earlier can be purchased for about $6 and these two balls (not the stands, those I had from earlier) I picked up for about $0.50. Not each: total. Including shipping.
Which is why I laugh so hard when I see a supplier on Etsy selling 4cm crystal balls with identical etching for almost twenty bucks a pop. For $20 I can get a 20cm ball if I look carefully enough.
