I basically looked around my lab and used what I found but there could be many variations. I used the end of a carbon fibre fishing rod (with the eyelets removed) as the guide and a cotton reel as the mass. This worked quite well as the reel fitted nicely over the rod which was shiny therefore having little friction. You probably don"t have a broken fishing rod but a metal or wooden rod about 1.5 m long would be fine....