To help with my wind turbine projects I have created a simple jig to wind coils. Using 2 steppers motors, some m6 bolts and some 3D printed parts I have created a very basic coil winder. The software was created using Flowcode 6. The Flowcode source code and SketchUp CAD files are both available in the downloadable files.
The motors I used were from a box of random reclaimed motors I bought on eBay some years ago. The motors both had a gear which I couldn't remove so the motor couplings will need to be tweaked for your own motors. I used 3 x M6 80MM bolts as the drive shafts and this gave the coupling a nice flat head screwdriver groove to get a good grip on the bolt. Hex head bolts would probably work even better. M6 bolts were used as these have a thread pitch of 1mm per revolution which simplifies things. My motors have a 200 steps per rev setup or 1.8 degrees per step. Other than that it's fairly simple, print out each part, assemble and then sort out the hardware.
If you want to copy my approach then you can use two of the Matrix Motor board with a IDC splitter cable or you can go down the custom circuit route like I did. Normally I control steppers using NPN transistors but as these motors are bipolar I had to use a 4 full bridge drivers to control the two motors.
Note that when the motors are turning at a very low speed the driver can get a bit warm. I may change the firmware to better deal with this in future.
The Flowcode project file contains a lot of code to process int values as 1 or 2 decimal point variables but without the overhead of using 32-bit floating point maths for the majority of the work.