Looking for an inexpensive option, I ran into an article posted to a CrossFit forum (http://www.crossfit.com), which provided details on how to build an inexpensive Kettlebell. I have since built 5 Kettlebells of various weights and have been extremely impressed by the durability of the product as well as the options we now have when working out at home.
Kettlebell exercises employ a wider range of motion than traditional dumbbells and typically involves swinging and explosive movements that utilize the full body. Because the weight is off-center from the handle, the movements demand greater stability and really target the core muscles.
Step 1: Materials & Tools
-1 bag quikrete pre-mixed concrete mix
-1 cheap rubber ball (under $5)
-26" of 3/4" or 1" PVC (sch40)
-Small quantity of sand
-1 Hacksaw or Jig Saw
-1 Heat Gun or Oven
-1 Bucket (for mixing)
-1 Small Garden Spade or similar tool (for mixing and transferring concrete to the ball)
-1 Pair of Scissors
Step 2: Prepping the Handle
For sizes & weights, I have found that a mini basketball (Size 3) will end up around 13 lbs. or so, while a full sized basketball will be just under 30 lbs. You can also adjust the weight of the Kettlebell by adding in less/more dense items (ie. lead or steel shot or washers, etc to increase the weight, or packing peanuts or similar to decrease the weight).
Use the hacksaw to cut the PVC to a 26" length. Depending on your preferences you may want a bigger or smaller handle, but I've found that 26" makes a comfortable sized handle.
Use Duct tape to cover the opening of one end of the PVC.
Fill the PVC pipe with sand.
Once packed full, use Duct Tape to seal the other opening of the PVC.
The sand is used to keep the PVC from losing its roundness when being heated up and shaped.
Step 3: Forming the Handle
There are two options that I've tried and both have worked well. The first is to use a heat gun to heat the PVC until it is pliable enough to bend and form the handle shape. The other is to use an oven. With the oven method, I would wrap the PVC with tin-foil, place it on a baking sheet and heat it at 350F for 10min. After that, the entire length of PVC is soft and ready to be bent.
Whichever method you use to heat the PVC up, you would then either bend it by hand (using oven mitts for protection) or use a template to wrap the PVC around to create the shape you want. Ultimately you want the PVC to be shaped like a triangle with nicely rounded corners.
Once the PVC has been bent, you need to keep it in this shape until the PVC cools again. Dipping the pipe in cool water will help speed this process up.
Once cooled, you have yourself a handle.
NOTE: if you are not happy with the shape of the handle, simply use a heat gun to re-heat the area of concern and re-shape it again.
Step 4: Prepping the Ball
With the handle complete, it's time to move on to the ball.
You need to cut the ball open so that the handle can sit half-way inside. The ball is being used as a form for the concrete as well as a nice rubber coating for the finished Kettlebell.
Cut a slit in the ball long enough to sink the handle to a suitable depth inside the ball. Be sure to insert the handle as a test to ensure the length of the slit is correct. Once the slit is complete, cut two (2) circles at both ends of the slit. The PVC pipe will sit within these circles. The slit will then be used as an opening to fill the ball with concrete and will allow the flaps on both sides to cover up the concrete on the finished product.
Note: This latest build was for the wife (hence the pink & white ball).
Step 5: Completing the Kettlebell
With the ball and PVC handle ready to go, you can move onto the last step: filling the ball and inserting the handle.
Pour enough Quikrete into your bucket to roughly fill the ball. Don't worry about being too exact, if you have a little too much, oh well. If you don't have enough, just mix some more.
Add just enough water (a little at a time) to the bucket and mix until the concrete mixture is a thick paste. Make sure it isn't too runny. If it is, just add more Quikrete to balance things out again.
Once your Quikrete is mixed to the correct consistency, use a small garden spade or similar tool to spoon the concrete mixture into the ball.
While you're filling, press down on the ball to create a slight dent in the bottom of the ball, this will keep the finished Kettlebell flat on the floor and will keep it from rolling around when you set it down.
Once the ball is mostly filled, insert your handle and set it to a comfortable depth.
Continue adding concrete until the ball is full. Make sure to shake the ball and lightly tap it on the ground to get the concrete settled to the bottom.
Once the ball is filled, check that your handle is still at your desired depth and is also nice and straight.
Once everything checks out, give the ball a quick wipe with a damp cloth to remove the excess concrete and let the concrete set for at least 24hrs.
After the 24hr set, wipe your Kettlebell down once more and you're ready to start swinging.
Step 6: Resources & Credits
Photos and Descriptions of Kettlebell Exercises by Mike Mahler
Kettlebell Videos (Youtube)
Picture 2 on Intro credited to JohnCalnan (Flickr) - Some Rights Reserved (see link for licensing info) - (Link)
DIY Kettlebell inspiration credited to Matt Charney on the CrossFit.com forum - (Link)