How to Make a Better Medicine Ball

Starting a new workout routine without a gym, I decided to get some equipment, including a medicine ball.  Medicine balls are great for enhancing simple movements into toning exercises just by adding a little weight, and challenging your balance.  The concept of the medicine ball is pretty simple - a weighted ball with some kind of tactile surface good for holding.  

However, in my searches for a DIY solution, everyone used basketballs.  I kindof get that - they would be pretty sturdy since they're made of thick rubber and they have the rubber bumps all over the surface for a good grip, but in sealing these up the only solutions I could find (or think of) is to use a **** ton of duct/gorilla tape, or to use a car tire repair kit, with the rubber worm and rubber cement.  Either patch solution seemed like it had drawbacks, since the tire repair kit means you have to fill through a hole no wider than 2 or 3 mm, and the tape peels and tears over time, which has obvious drawbacks.

I decided to see what I could do with a soccer ball.  I think my solution is durable, elegant, and versatile, hope you enjoy!

Step 1: Gather Materials

What you will need:
-Cheap soccer ball (but with sewn sections) (I got mine for $8 at target)
-50# bag of sand or quickrete would work if you want a denser, harder ball ($3.50 for play sand at home depot)
-needle for inflating soccer balls (optional) ($1)
-super glue or bike tube repair kit or rubber cement (on hand)
-duct tape or gorilla tape (on hand)
-sharp knife (on hand) 
-metal pick, seamripper, or other tool that can be used for pulling stitches apart (on hand)
-funnel
-small cup
-strong thread (I think mine was made for sewing upholstery) (on hand)
-heavy gauge (maybe hooked) sewing needle (on hand)

All in all, I spent less than $13 to make my 8-pound medicine ball

Step 2: Open Up Your Soccer Ball

Pick a hexagon that you don't like (I tried to pick one close to opposite of where the inflation hole was), and use your knife to carefully cut through a couple of the stitches on one side of that hexagon.  Use some kind of metal pick or similar to undo the stitching from there, removing the stitches from all but one side of the hexagon, so it becomes a flap.  Make sure to get as much of the unstitched thread removed from the ball to keep everything looking clean.

Once you have made your flap, while the ball is inflated, cut about a 1" slit into the inner bladder of the soccer ball.  Make it big enough that you can insert your funnel, but not too big (we have to close it back up in the end)!  Try not to put your fingers in the hole to pick up the ball for any reason - I did this and it made the cut propagate another couple inches, making my repair job more of a hassle.

Step 3: Fill Your Ball

Now, in a place you don't mind getting a little dust in, stick the funnel into the slit in the soccer ball's bladder and use the small cup to fill your ball with sand.  Every now and then tap your ball to help the sand settle and fill the whole bladder.  This might take a while depending on the size of your ball, so play some music or something.   Go ahead, I'll wait.

Step 4: Close Up the Bladder

Once you have the ball almost entirely filled (as full as you want it), use a damp paper towel to wipe dust off the bladder and let it dry off.  Try to set the seam cut into the bladder together so you don't have to hold it, then apply your superglue, rubber cement, or bike tube repair kit, per instructions.  To help you out on this step if you use the superglue (and maybe the rubber cement), is to put a tissue down on the glue.  This will help speed up the curing, as well as holding the slit closed as it cures.

Next, tape up over the sealed cut with your duct/gorilla tape to provide some structural strength to your seal.  I used one strip along the cut, then a few long strips going the opposite direction, going under the edge of the outer ball.

Step 5: Seal the Deal!

The final step is also the most time consuming and tedious.  Take your time when sewing the flap back down onto the ball - it will be the only part you can see when you're done, so it should look good, but there's also the risk that if you put your needle too deep into the ball that you will pierce the inner bladder, and make a hole for the sand to leak from.  I used a heavy-duty curved needle shown in the photo, and about 6 feet (3 feet of double-length) upholstery thread.  Put a big knot on the end after threading the needle so it doesn't pull through.  I basically tried to use all the same holes from the original stitching when I went through, a basic stitching pattern is all you need (I don't think you can do much simpler than I did, just a single pass going from one hole to the next).  Make sure to tie a good knot when you're done so it doesn't untie and you're done!

I weighed my ball on a kitchen scale when I was done, and with a size 3 soccer ball (for kids' leagues, about 7.5" diameter) my medicine ball weight about 8 pounds 2 oz.  Size 4 and 5 balls are larger (8 1/4" and 8 1/2" respectively) and would weigh more, maybe up to 10 lbs for a size 5 filled with sand.  Another way to increase your medicine ball weight is to fill with rocks first, and then filling the cracks with sand, or to use quickrete mix, which can be up to 80 pounds for a bag the same size as the 50 pound bag of sand.  I would guess with that you could get a size ball up to around 16 pounds pretty easily.  

Also, this is my first instructable, so please let me know how it was, and if you have any tips for the future!   Thanks for reading!