Thank you Terry!
To be honest I thought I'd better work my way through the Arduino starter kit before making any decisions about anything, incl. stepper specs. Bottom line I'm leaning towards having some arms 3D printed, which need to be rotatable using steppers. The load will be minimal, but physical size is a consideration. I'm hoping that by 3D printing the arms I can design the arms round the steppers and come up with a nice connection between the two that allows for slow, sensitive, non load bearing rotation of three arms, each a semicircle inside the other.
I know it's going to be quite a lot of work and probably a lot of trial and error but I'm fine with that, I just want to make sure that I'm heading in the right direction in terms of the bits needed to control the whole thing.
Many thanks again