The most important problem about the Apple Watch is beyond dispute charging it. Many times you should carry the charging cable with you which is 1m long and not easy to unwrap when you pull it out of your bag with other charging cables.
So, if you want to carry your Apple Watch charger with you without getting annoyed here is a cost-free solution (assuming you already have an iPhone and kept the earbuds that case came with it.)
Step 1: Get the Case Ready
First of all, pull off the cable wrapping part and have a nice empty case of earbuds as you see in the first image.
Then, just stick your apple watch chargers head in the middle of upper/transparent part of your case, be intuitive and use any tape or sticky band you had. For example, I just used a two-sided scotch tape
Step 2: Wrap the Cable
Start wrapping your cable around the inner side of the case, try to wrap as dense as you can and do not go higher than the box itself.
Do not leave the cables loose
Step 3: Close the Box
If you are satisfied with the earlier steps, try to close the earbuds case to see if it fits ok.
Do not hesitate to try a few times wrapping the tighter and better, because you will only do this only once...
Step 4: A Few Tips
After a while the charger loosened and stopped charging through to box, to avoid that you can attach something to the bottom of the lid to support the charger head
Step 5: Get the Cable Out
As you can keep all the cable and USB inside the box, you can leave the end of the cable out and close the box
To do that carve the bottom/white part of the case a little as you see in the images
Step 6: Result
For those who have hard times to believe that would work, here, is the photo of the working charger