[Quick update: I still use the paper hand and arm trainer I made for this instructable (05.06.2018), so it is much more durable, than I would have expected ]
Playing with bend paper rolls, I noticed, when holding them with one hand on each side, I can angle my hands and this will turn the role in my hands.
The tighter I held, the harder it was to angle my hands.
I made it more stable and added handles, so that the turning role didn't rubb directly on my hands.
The result was a simple training tool, with that I could exericse my grip strength against my arm and wrist strength.
The muscle trainer can be used while watching netflix, while traveling, and in between work.
I like to do small sessions, to exercises my arms and get a free head.
You need about 30 sheets of paper and tape
Step 1: Roll and Wrap
Take 10 sheets of paper and fold them near the middle of the small side.
Roll the paper sheets from the folded side. Roll very very thight, best on a table. Hold the role against the table and shift it half over the edge, allowing you to grab the role with out releasing pressure against the role.
Hold the role and wrap it with the tape. Roll in the direction of the paper sticking out and draw the paper sheets even tight togeter.
Wrap a few layers of tape around the middle of the role. This layers will hold the role together, when you bend it, so wrap a few more.
Press the role flatter in the middle, creating a weekness.
Step 2: Bend
At the point, where you pressed to role together, roll a few thight layers of tape around it, to protect it from breaking when it is bend.
Carefully bend the role where you pressed it together and roled the tape around it to make it more stable.
Step 3: Support the Angle
To increase stability wrap a strip of paper tightly in an eight like shape around the angle.
All edges of the paper strip have been folded inside, to stop it from tearing. But it is ok, if it teast a little bit.
Wrap tape tighly around the angle, with the paper strip.
And add an other paper strip in the same way.
Then make a third paper stripe and wrap it around the middle of the angle, that the eight shape has left free.
This way the eight shape can not just shift to the middle, when you try to straighten the paper role.
Add an other layer of tape, all the way from the angle to the ends of the role, all in one strip of tape.
To avoide the tape being brushed of, when turning the handles later, wrap over the edge of paper role.
Do this by wraping over the edge abit, extending the edge. Wrap a few times over the edge, until you have enought tape there, well connected to the rest, to twist it into a candy wrap like close. Twist the ends to keep the tape from unrolling.
Step 4: Add the Handles
The handles have to be a little thicker, else they will wrap around the paper role tighter and tighter, until they can no longer be turned. All tape has to be on the outside, because the paper role would rubb it of quite fast.
Fold the edges over and secure them with tape, to make sure you don't cut your self, when using it.
Do not roll the handles around the role, but make a loop, with the paper sticking out on both sides. This way it can not drag it self closer around the paper role, until it can no longer be turned.
Lay the loop around the paper role, and press the ends flat onto each other. Fix them togheter with a stripe of tape near the loop.
When using wrap your fingers around the thick side of the wing like handles, so that your palms and finger tips press against the thin side of the "wing". This alos keeps it from wrapping around the paper role.
When it gets stuck, change the direction, to unwind it.
Now you have a nice and cheap tool to train your arms in front of the television, or on travels.
Step 5: Usage
Grab the handles and press them, trun the handles against the force of your hands.