Design how you want to build the roller coaster (There is no set design for this. Just be creative and come up with your own design!) Always make sure the highest point should always be the starting point.
Once you finish your design, mark where you want to nail your scrap woods which will support your track.
Using screw driver, fix scrap woods on the plywood.
Cut little less than a half of pipe insulation (when viewed from side). If more than a half is cut, there is a possibility where the marble will roll out of the track.
Connect multiple pipe insulation (if needed) using duct tape.
Attach pipe insulation to scrap woods using duct tape.
When making a loop, make sure it should be firmly fixed onto the scrap wood. It is better to have a slight vertical oval shape than a perfect circle.
Adjust the track as you roll marble on it. The marble might not have enough energy so it will not climb the loop or roll out of the track. Multiple adjustments may be required.