A lead weight and a few miles of good fish line.
The oll industry built a few test chambers capable of 20 to 25ksi; I don't know if any still operate commercially .Try former Amoco R&D in Naperville IL, may be BP (they wouldn't know how to operate it) on Warrenville Rd. Former Cameron facility NW of Houston (Telge Rd ?). Former Mobile Oil facility , Farmers Branch TX ( DFW area). Maybe someone at "Stress Engineering" in Houston could help.