sorry guys the lowest cost is no enclosure for me😂

ZYZ is used in AR4 software to calculate Rz,Ry and Rx. It DOES NOT appear to be ZYX but I could be wrong. Calculation for ZYZ Euler angles can vary depend where you get your source which is mostly on google. Can be frustrating when one is trying to learn.

still mystery to me

do you still get 3.3V on your teensy board? if not then your board is damaged

hard to troubleshoot noise related issue over email. Suggest to put a probe on the encoder line(s) to check for noise source which can come from power supply in your setup. The encoder is neither cancel or generate noise. You can try to external line driver to convert differential outputs from encoder to single ended. But that requires wiring modification from encoder and external line driver device.

The encoder in AR4 has differential outputs or complementary signals for noise immunity. When noise is present on a differential pair, the differential receiver cancels the noise aka common mode rejection. Not sure why AR4 only used single ended A and B signals. In that case a shielded cable can help if noise is a concern. A shield if not grounded has no value.

Thank you for your help as i am new to the 3D printing. It worked!

Okay does that mean flipping the part is same thing as printing the J2 Arm Space Upper TWICE?