This is what I've used to mount these spring-loaded take-up spools for my polargraph machine cords. It has holes to put in a length of 10mm diameter aluminium tubing, that you'd mount the spools on.

The spools are taken from a retractable washing line (http://www.argos.co.uk/static/Product/partNumber/8501240.htm).

This is designed to be mounted onto the top edge of a 18mm board. Hammer a length of 10mm diameter aluminium tubing into the socket, and cut a slit down the centre of the tube. This is to slip the tongue of the spring into.