3D Printed Optical Encoder 

Looks cool mate.

Old ball type mouse used these code wheels that moved the pointer on the computer screen.

Haha, they were inaccessible then due to cost. Now I'm noticing less stock, and I have to get units that aren't all the same number of counts per rotation. So we're back to building these things ourselves XD

Briliant idea. :)

hello, do not check the code but I think what is happening is that you do not have a solid reference point, maybe a missing tooth or more than one alternating sequence would give a better resolution, but I do not consider that engine is the most suitable by its arrangement of coils, perhaps a engine of 4 poles out of phase at 90 ° would be a solution to stop the movement of the shaft.

Which arduino are you using? Looks too slow. Are you using interrups? In this space interrups are even slower. Use assembly in tight dedicated loop. Best you'll get is 600e-9 second response time with 16mhz clock on arduino mega2560. You know, you may try esp8266 with the wifi disabled if you are looking for common cheap parts.

why not use a ITR9608, they are ~0.1 US from aliexpress? Are you worried about size?

if you are still alive, please help me, I need to know your voltage output and resistors, I've spent weeks desperately trying to do this, please.