Basically I need a suitable electro-mechanical movement to bring a model of a chair in a simple up and down movement as part of a project building an appliance for people with a disability. This chair would act as an aid to lower disabled users into and out of a model bath tub and would need to pivot in its fixed position a full 360 deg. but that should not be a problem to construct. The main problem is constructing a non-complex electro-mechanical mechanism to bring the chair up and down in a linear fashion (preferably on a pole). I was thinking rack and pinion but this would need some kind of drill table collar clamp, which in model size, would be unable to source. Any ideas for mechanisms? The model I am trying to build is an attempt to replicate the bath hoist here: http://www.handyhealthcare.co.uk/mobility-aids/bathing/bathing-hoists/oxford-mermaid-bath-hoist.html Any advice would be greatly appreciated.