Print it in Ninjaflex at 70mm/s with the Flexion ExtruderI printed it with 15% fill to leave it pretty squishy. Makerbot Replicator (original version with the MK8 spring loaded extruder upgrade). Extruder temp: 215 C Platform: Room temp, bare aluminum, glass, or Kapton tape all worked well Retraction Settings (In Skeinforge under Dimension tab): Minimum Travel for Retraction: 1.0mm Retraction Distance: 2.0mm