This is heavily based on the Xaphoon, a version of a mini saxophone with the sound between a clarinet and a saxophone. All parts work well in PLA and PETG according to my tests. I haven't tried ABS, but this should work just fine in that too. The video (https://youtu.be/deijf9jOcm4) demonstrates some of the 3DPminiSax's capabilities and highlights my poor playing ability. Please don't hold it against me. I designed the parts in TinkerCAD.
The three main parts (top, bottom, and mouthpiece) should go together with a friction fit. However, I achieved much more consistent play after using an epoxy resin to glue them all together. The video provides some instructions on assembly.
I did not notice a discernible difference in tone between the curved bell and straight bell version. I designed the curved bell thanks to recommendations by my more musically inclined brother and sister. At the base of the bell is a tag/stand. In my own versions I put my name on it. If you are comfortable using tinkerCAD, adding your own name should be pretty easy.
I've successfully used both a tenor and an alto sax reed on the mouthpiece. I recommend starting with a 2.0 strength tenor sax reed. (10 pack: https://amzn.to/2Lnppkk, 3 pack: https://amzn.to/2S66EEE).
For those who want to learn to play, try songs in the F major chord (b-flat scale). This way fingering is straight forward. (closed: @ open: O) Fingers are Left to Right, Top to Bottom. I've included some songs I arranged and play in the video.
C: thumb:@ fingers:@@@@@@@@
D: thumb:@ fingers:@@@@@@@O
E: thumb:@ fingers:@@@@@@OO
F: thumb:@ fingers:@@@@@OOO
G: thumb:@ fingers:@@@@OOO@
A: thumb:@ fingers:@@@OOOO@
Bflat: thumb:@ fingers:@@OOOOO@
C: thumb:@ fingers:@OOOOOO@
D: thumb:O fingers:@OOOOOO@
E: thumb:@ fingers:OOOOOOO@
F: thumb:O fingers:OOOOOOO@
G: thumb:@ fingers:O@@@@@@@
A: thumb:@ fingers:O@@@@@@O
The ligature and straight bottom are the same as kyopi's and Old_Holborn's designs respectively.