The experiment (Project Apeiro) aims to determine cosmic ray flux in the lower stratospheric regions of the atmosphere by deploying a measurement instrument on a High-Altitude Balloon platform. This paper illustrates the design and construction of the experimental equipment and also highlights the precautions and tests undertaken to qualify the instrument for a near-space flight. Cosmic ray flux is measured by using detectors constructed with an optically coupled combination of scintillator blocks and photo-multiplier tubes. The signal from the detectors is recorded with a high speed data acquisition system (DAQ). The flight computer acquires data from the DAQ and other sensors and stores them on a memory. The flight data is also continuously transmitted to the ground station over a telemetry channel. The flight was conducted from Hyderabad, India on February 2, 2019. Preliminary analysis of the flight indicates nominal operation of all equipment, and has been presented in this paper.