I printed in PLA two similarly shaped components, one with a 5cm by 5cm right angle triangle cross section extruded by 1 cm and the other the same but with a slight parabolic concave on the hypotenuse (ie slightly less volume). I set the infill density to 90% and so was surprised that the latter parabolic one weighed 50% more than the triangle. It should have weighed 18% less. I cleaned the nozzle before printing the parabolic one which may have meant the triangular shape was using less PLA and certainly the print looked less smooth. Are there any other explanations why the weights would be so different from expected?