How to make Gymnastics/Fitness Rings from PVC Conduit

Step 2 Determine how long you need to cut your pipe

Unless you can find a 10-inch inner-diameter cylinder, you might need to calculate how long to cut your pipe rather than using my dimensions. Fortunately, there seems to be some room for error. If you cut it too big, you can squish the ends together and trim them once the pipe cools. This could deform the handles a bit. If you cut it too small, you may have trouble keeping the rings in a circular shape.

According to Wikipedia, dimensions for gymnastics rings are as follows:

Inside Diameter of the rings 18 cm (~7.06 inches)
Thickness of the rings 2.8 cm (~1.10 inches)
Total Diameter of the rings 23.6 cm (~9.29 inches) (thickness 2.8 cm, 18 + 2.8 * 2 = 23.6)

http://en.wikipedia.org/wiki/Rings_(gymnastics)

Depending on the diameter of your cylindrical object, however, your dimensions might vary. I used a metal trash can that has a 10-inch inner diameter so my dimensions were as follows:

Inside Diameter of the rings = 7.5 inches
Thickness of the rings = 1.25 inches
Total Diameter of the rings = 10 inches

I estimated the length of pipe I needed by calculating the circumference using the average of the inner and outer diameter of the rings, which is the circumference of the middle of the pipe:

average_diameter = (10 + 7.5) / 2 = 8.75
length = average_diameter * 3.1415

In retrospect, I probably should have used the circumference of the inner diameter of the rings so the ends wouldn't have to be squished together as much (this slightly deformed the rings, resulting in more oval-like hand holds).