Entry level 3d printer
#16
If you are interested in learning to design parts, YouTube has tons of great tutorials on Solidworks (for which a license can be had cheaply or free if you're a student) and other design software!
#18
There are different levels of durometer (softness) for TPU's. I just got some sainsmart TPU and its pretty stiff vs something like NINJAFLEX. The printer you have pushes the filament instead of pulls so the stiffer TPU's will be better (I have a ender 3 which pushes as well). You may want to see if there are any mod's to improve TPU prints with your printer but unfortunately the push style bowden tube style printers will always have a limitation with TPU.