PLA, NinjaFlex We used a 6mm brim to insure the bottom doesn't curl up while printing.The seat part take about 30 hours to complete. Z-Hop is used to prevent any collisions with the print head and any edges that might curl up. We used infill angle offsets to increase the strength of the seat. Infill angle offsets: 45, 60, 90, 120, -120 The stool feet are printed in original Ninjaflex to make them grippy, but you could also use semi-flex or cheetah.