Most collapsible hoop designs I've seen feature removable sections that snap back together with the help of elastic straps. This Instructable features a more sexy folded infinity method, reducing the hoop to two smaller circles that can be worn across the body. I like this design for taking my hoop on public transit to hoop get-togethers in the city.
Step 1: Tools and Supplies
* polytubing (see Notes on Polytubing, below)
* connectors, 2 per hoop (3/4 inch connectors for 3/4inch tubing, 1inch connectors for 1inch tubing)
* decorative tape (electrical tape works great and is available in a variety of colors)
* utility knife
* hack saw or ratcheting pvc pipe cutter
* heat gun or hair dryer
Notes on Polytubing:
* 3/4 inch 100psi or 160psi, or 1inch 100psi can all be used to make hoops. For beginners, 3/4 inch 160psi seems to work well.
* 1inch 160psi tubing is also available, but will make a very heavy hula hoop.
* Polytubing is commonly sold in 100ft rolls. This is enough for approx. 8 hula hoops.
* Tubing can be hard to find in some areas. It is mainly used for lawn sprinkler systems. Call around to big-box hardware and irrigation supply stores to save time and gas.
Step 2: Measure and Cut Tube
Decide how large a hoop you want. It should be somewhere between waist and shoulder height. The ones I've made are about as tall as my natural waist when i stand them on end.
Mark the spot to cut, and then use a hack saw or PVC cutter to make the cut. PVC cutters make a nice clean cut, but I didn't have one on hand, so I used the hack saw method.
If you want a standard non-collapsible hoop, then you're done cutting and can go on to the next step. To get a collapsible hoop, cut the length of tube in half using the hack saw.
You can see in the picture that the hack saw left a mess of burrs around the inside and outside of the tube. Use a utility blade to clean those up and smooth the cut ends before going on to the next step.
Step 3: Insert Connectors
Use the heat gun or hair dryer to heat up one of the tube ends. Move the gun around constantly so you don't melt the tubing. Once its good and warm, slide the connector halfway into the tubing. I've found that its easiest to get the connectors in by pressing the end onto a hard surface such as a workbench instead of trying to use just my hands.
Repeat for the other end of the hoop half. Your project should look like the second picture below.
Join the hoop halves together, inserting the other halves of the connectors into the empty tube ends. It should look like a plain black hula hoop when you're done this step.
Step 4: Decorate Your Hoop
I used two colors of electrical tape, and wrapped them in opposite directions.
Once you're done decorating, use a utility knife to cut the tape where the connectors were inserted into the tube.
Step 5: Collapse Your Hoop for Travel
Folding the hoop takes just a few seconds.
* Position the hoop with the joins at the top and bottom of the hoop.
* Grasp the tube near the top join. Place your foot on the hoop near the bottom join
* Push down and slightly away from your body. The hoop should begin to take a figure-eight shape. NOTE: The tubing is stiff, so don't be afraid to apply some pressure to get it to fold.
* Fold one half of the figure-eight on top of the other. The tube will twist on the connectors at the joins.
* Sling the folded hoop across your body and go!
PS: Don't store your hoop in the folded position. It might conform to that shape and be out of round when you unfold it. It's hard to hoop with a wobbly hula hoop!