||In this thesis, I explore the sample preparation for 3D hexagonal phononic crystals with volume fraction 69.8% consisting of tungsten carbide balls (1mm-diameter) or steel beads (1.5 or 2mm in diameter) as scatters. Different matrices are tried, including water, tin-lead alloy (63%Sn), paraffin, polystyrene and other polymers, whose absorption coefficients are also studied. Temperature and pressure control in matrix fill-in process is studied as well as TC ball surface wetting improvement. Transmission measurements are taken when using three different environments including Aluminum waveguide, acrylic water tank and water immersion. Pulsed ultrasonic techniques are used through the measurement. Three different couples of piezo-electric transducers offer the measurement frequency range from 0.1 to 10MHz. Transmission spectra along two different directions are obtained through 22 layers TC/water phononic crystal held in acrylic box. Overlap regimes for transmission coefficient dips are found. Solid form phononic crystals with paraffin and polystyrene as matrix are successfully made, through which wide transmission dips are observed. Scatters with different sizes are tried and observed dips shift to lower frequency range for bigger scatters. Further improvement and future work is also discussed.