Art Glass Marbles hand made by David Kingman in the USA, more specifically Oregon. One of a kind Borosilicate art marbles. Extra kiln annealed for strength. Money back if you are not completely satisfied. Time required to do these range from 20 minutes for a very simple and small marble to many hours for more complex and/or larger sizes. The marbles can be signed and numbered in titanium to make them Identifiable for collecting or left unmarked.