This paper presents modeling and experimental results of untethered flight of stereo-lithographically printed MEMS microfliers propelled by radiometric forces. Analysis of the physics behind radiometric microscale flight is presented, followed by detailed experimental results. The present work further enhances our understanding of the underlying principles of these microflier designs as well as demonstrates methods to build designs using 3-D stereo-lithography. This paper verifies that the perimeter and not the surface area of the flier is the key factor in determining the force experienced during flight. Despite differences in underlying physics, similar preference (perimeter over surface area) is observed in biological microscale flight.