here are some videos to show you the result
http://www.youtube.com/watch?v=cYPD5ZZ4OC8
http://www.youtube.com/watch?v=KAPiEbwcEWk

And now in ski condition
http://www.youtube.com/watch?v=63XprUl5DGE
the camera was deliberately oriented too high to see the joint, but in normal use it should move the camera closer to the bottom.

to finalize this item you will need :

• a ball bearing 608 (in gray on drawings)
• 4 wood screws 3mm and 10mm long.
• 1 metal screw 4mm and 30mm long
• 1 metal screw 5mm and 50mm long

for the tube I used a tube to protect the electric wire of 22mm diameter and for my first test tube was 80cm (with a fastener in the middle)