This paper describes an experimental design technique for determining the optimum surface finish, dimensional accuracy and porosity of a part built by Fused Deposition Modelling (FDM) process and mathematical modelling of the process parameters. It also explains the contribution effect of slice height, raster width, air gap, orientation and raster angle on surface roughness, dimensional accuracy and porosity. Experiments are done by Taguchi's design of experiments with two levels. The analysis is done by both ANOVA and RESPONSE SURFACE METHODOLOGY. The best and optimum process parameters found out to be is slice height of 0.1270 mm, raster width as 0.6096 mm, air gap 0 mm, orientation as 30° and raster angles as 0°. © 2016 IEEE.