Fused Deposition Modelling (FDM), or Free Form Extrusion (FFE), is a popular method for 3D printing by means of a polymer filament that is extruded and deposited according to a sequence defined by a Computer-Assisted Design (CAD) file. Complex 3D parts can be obtained without a mold by adding successively material layer upon layer. Despite its popularity, FDM/FFE parts often exhibit shape distortions and weak mechanical properties, which are due to the temperature gradients developed upon cooling and to insufficient bonding between adjacent filaments, respectively. Consequently, for process engineering and optimization purposes it is important to identify the cooling history of a part. A computer code was previously developed by the authors to predict the temperature field and the degree of adhesion between adjacent filaments for 3D printed parts [1]. The code includes a routine to solve the energy equation, an algorithm that activates the boundary conditions as deposition proceeds, an adhesion criterion [1,2]. In this work, we discuss the effect of changes in the geometry of a representative part on cooling and adhesion. The aim is to obtain some scientific guidance on the design and manufacture of 3D printed parts. [1] S.F. Costa, F.M. Duarte, J.A. Covas, J. Mat. Proc. Technol. 245 (2017) 167 [2] S.F. Costa, F.M. Duarte, J.A. Covas, Virtual Phys. Prototyp. 10 (2015) 35