Frank Sturm visited PANArt and made a video showing Felix Rohner building a handpan by simple tuning, a tuning method based on the “string like” modes of oscillating plates with geometric 2:3 ratio.
In his accompanying text Frank says:
A usual Hang upper shell was used and three rounds of tuning were carried out interrupted by two heating procedures in the oven. The first round is shown in full length in the video, the other two as excerpts. The tuning time was round about an hour. Then the upper shell was glued to another cut shell that was left over from Hang Gudu building. This way a handpan without domes and without a closed chamber that works as a Helmholtz resonator were made, a handpan that doesn’t copy the characteristic Hang design.
There are a lot of high-priced handpans on the market made by simple tuning. Are those prices really justified? I wonder why a lot of handpan makers are using domes for their instruments although they are not required. Isn’t it confusing the customers when the famous Hang form is copied?
I recommend to open the video on Youtube 
and read the full text.