TPU (NinjaFlex) has a reputation for stringing and being difficult to #3dprint with. Once you get your settings down (Lots of retraction, print slower), TPU is a fun material to print!.
I print a lot of flexible #fidgets and adaptive items for sale at fairs, so post processing TUP is always an issue. flush trimmers may not work on the material, but I found spring loaded scissors / bonsai scissors are great for cleaning up the fine hairs / stringing you have on the print!
