Yesterday i have installed the decorative acrilics that for the upper loop of my pinball machine.

The acrylic parts are 29 milimiters above the playfield, the exact height of the posts I decided to use (the one I have modeled in FreeCad). I have chosen this one because it is higher than the diameter of the ball, so that the ball will not touch the acrylic parts which are fragile (unless it jumps for some reason). So, I'll need something to guide the ball in the upper loop. I though of using metal guides, but I need advice on that. What would you suggest?

More photos at http://www.flickr.com/photos/felipesanches