Hi Jo, that is looking neat, well done!
I followed Paul Chasse design, but made my own (see
https://www.flickr.com/photos/977301...7634741430337/). You need to be careful not to make it too tight.
Too tight is when the motors require more than ~600mA (if my memory serve me right), as then the controller will give you an 'over current' error. If you keep it around 400mA when slewing at max speed you should be fine.
cheers,
Bram