An experiment was carried out by Gudenrath and Whitehouse with the aim of re-creating the Portland Vase .
An outstanding example of the free - blowing technique is the Portland Vase , which is a cameo manufactured during the Roman period .
An experiment was carried out by Gudenrath and Whitehouse with the aim of re-creating the cameo   .
An outstanding example of the free - blowing technique is the Portland Vase , which is a cameo manufactured during the Roman period .