A mechanical design is reported for constructing a multi-pinhole (MPH) collimator that will be used with a fanbeam collimator for high spatial resolution and sensitivity imaging of the striatal region of patients suspected of having Parkinson's disease. The design strategy was to alter an existing commercial pinhole collimator by adding the MPH components while keeping the portion of the collimator that attaches to the head of the gamma-camera. The MPH array consists of nine apertures focused at a common point at the center of the striatal region of the brain with their entrance and exit ports such that no overlapping occurs of their projections on the detector of the gamma-camera. A shutter mechanism is included at the side of the aperture plate towards the detector which will allow opening an additional eight apertures to image with increased sensitivity, but with the projections multiplexed with those of the original nine pinholes. Testing of the material properties of the alloys used in construction of the MPH collimator provided validated values. These were used in a SolidWorks simulation of material deformation due to gravity during imaging to ensure safety and imaging accuracy. The SolidWorks CAD design of the MPH collimator was imported into the GATE Monte Carlo package to simulate brain imaging and to test striatal imaging with the model geometry.