With　the　rapid　development　of　the　internet　of　things,　the　simple　preparation　of　sensors　has　become　a　challenge.　The　present　work　presents　the　simple　preparation　of　flexible　sensors　by　using　the　fused　deposition　modeling　(FDM)　3D　printing　combined　with　the　microwave　radiation-assisted　treatment　of　the　thermoplastic　polyurethane　(TPU)　with　carbon　nanotubes　(CNTs)　as　conductive　fillers　to　create　the　flexible　sensors.　The　as-prepared　TPU/CNT　composites　exhibit　the　7.27　MPa　tensile　strength　and　401%　elongation　at　break,　similar　to　those　of　the　pure　TPU.　After　200　tensile　cycles,　the　TPU/CNT　composites　can　still　stably　convert　pressure　into　electrical　signals,　which　can　be　used　as　flexible　sensors　with　high　sensitivity　(0.879　kPa-1).　In　addition,　shoe　insoles　and　finger　cover　with　sensing　performance　are　fabricated　through　the　FDM　3D　printing　technology,　demonstrating　the　potential　of　the　sensors　to　monitor　human　gait,　finger　straightening,　and　bending　movements.　The　as-proposed　method　involves　the　embedding　CNTs　as　conductive　fillers　on　the　surface　of　TPU　to　form　the　TPU/CNT　composite　conductive　layers　on　the　surface　of　TPU,　which　is　beneficial　for　maintaining　the　elasticity　of　the　polymer　matrix.　The　challenges　in　preparing　stable,　low-cost,　and　scalable　flexible　sensors　and　highlights　of　the　advantages　of　3D　printing　technology　in　manufacturing　flexible　piezoresistive　sensors　are　also　deeply　discussed.　A　microwave-assisted　method　for　rapid　construction　of　conductive　networks　on　the　surfaces　of　3D　printed　parts　is　proposed.　The　as-prepared　TPU/CNT　composites　can　still　stably　convert　pressure　into　electrical　signals　with　high　sensitivity　(0.879　kPa-1)　after　200　tensile　cycles.　The　TPU/CNT　composite　flexible　sensors　demonstrate　the　potential　applications　in　monitoring　finger　bending,　discriminating　running,　and　walking.　image