Johann Matthias Hagelstein (1706–1758) was an organ builder from Lüneburg, Germany. He was a student of Matthias Dropa, who himself had studied under the famous organ builder Arp Schnitger. Hagelstein's most notable work is the organ he built for St. Georg Church in Gartow, which was his first and only organ. The project, completed around 1740, was financially challenging, as the final costs significantly exceeded the original estimate. The refusal of the client to cover these additional costs led Hagelstein into financial ruin, ultimately causing him to declare bankruptcy. Despite this, his work remains a testament to the craftmanship and traditions passed down from the Schnitger school of organ building.

https://de.wikipedia.org/wiki/Johann_Matthias_Hagelstein