This is my second print using TPU, after the calibration cube. The material is soft. The main strategy is to abandon all hope of retracting the elastic filament. Instead, to maintain a constant feedrate so the pressure in the hotend can stabilize, cross perimeters as little as possible, and do rapids as fast as possible.
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any quality digital calipers that measure in both inches and millimeters will go a very long way towards reverse engineering. I'm still using an inch dial caliper from 2014.
Btw, if you are worried about learning the wrong software and wasting your time, don't be. FreeCAD is now good enough that there isn't a significant difference between FreeCAD, Fusion 360 and SOLIDWORKS when it comes to basic modeling. They all work in the same way, and require you to think of what you are doing conceptually in the same ways.
And most of the time it isn't difficult to use the program you aren't as familiar with for one specific thing only it does well and then do the rest of the project in your program of choice.