The engineering design related physical properties of castor seeds found in North West Ecological Zone of Nigeria were investigated. The properties will enhance design of production, handling, processing and storage equipment for the crop. Four different collections of castor seeds at 12% (db) moisture content were used in the study. The obtained results for the collections range from 9.38-15.77, 5.88-12.62, 4.21-7.47 and 6.15-11.41 mm for major, intermediate, minor and geometric mean diameters, respectively with Braz 4 having the highest dimension and BKB has the least dimension. The sphericity, thousand seed weight, volume, porosity, bulk density, surface area and angle of repose were found to be in the range of 66-72 and 45-62%, 122.97-623.52 g, 166.05-308.07 mm³, 33.33-41.24%, 537.02-479.23 kg/m³, 118.82-409.00 mm² and 28-30º, respectively. The results revealed wide variations in some of the physical parameters determined indicating that differences in varieties are important in equipment design and development.