I posted a perspective bar set up some time ago, and thought I would revisit a 3D approach. This is what I ended up with.
The bar rises and falls in relation to whatever conky output you feed it. The script can be found here.
It took a crash refresher course in basic trigonometry to get everything working and I can't guarantee that if you try the script it will work. The bar looks as I wanted it to, but I was hoping to be able to define simple coordinates and have multiple bars generated that all fitted together.
This didn't work out in this script as I the math I was using wasn't calculating the right perspectives for subsequent bars.