Introduction: Stickytape Sensors
Basically you just have to get the conductive surface and Velostat ratio right. I find the following methods work best. As little conductive thread as necessary to cover the sensitive surface. For up to a two cm wide strip, it can be enough to have a single thread running down the center of the strip and three layers of Velostat in between each thread.
Stick a stickytape bend sensor to your wrist with some extra stickytape!
Make your stickytape bend sensor and hook it up to your computer in less than 4 minutes!
This video shows the full process of making a stickytape bend sensor and hooking it up to your computer in less than 5 minutes.
This video shows the graph of a super slim stickytape bend sensor inside a regular drinking straw.
Step 1: Materials and Tools
The materials used for the sensor are easy to buy online. They are also relatively cheap. I would guess that you could make up to 1,000 sensors for less than 30$
When shipping to north America, I like to order from LessEMF because they stock all three essential items, are quick to ship and the prices are reasonable.
Velostat is the brand name for an anti-static plastic manufactured by 3M. The plastic bags in which sensitive electronic components are packaged are made of this material. It also runs under the names: anti-static, ex-static, carbon based plastic, ESD, Linqstat (made in china), Lagerbeutel (German for storage bags)&
So you can also cut up one of those black plastic component bags if you have one at hand. But caution! Not all of them work!
- Any kind of stickytape will work, but it can be nice to use a duct (gaffer) tape for its flexibility and robustness. You will find a wide selection of tapes at your local hardware, office supply store and stationary stores.
Step 2: Tape
Cut two identical pieces of stickytape the size and shape of the sensor you would like to make. Basically every sensor will be pressure sensitive and if you bend it then you can call it a bend sensor. I tend to make my bend sensors lengthy in shape.
If you like you can download these stencils for guidance. But i really think this Instructable is more fun with less precision and more free-form.
Simple Bend Sensor >> 
NOTE: As in all steps, take a close look at the pictures to better understand my description. Plus, always think about different ways to do things. Maybe you can make these sensors even simpler or possibly improve their performance!
Step 3: Thread
With lots of patience, place a piece of conductive thread on top of the sticky tape so that it covers the area that you want to be sensitive to pressure, but really only put as little as necessary to cover this area. Too much conductive surface will ruin the stability of your sensor. Make sure that one end of the thread is far from the edge and the other extends beyond the edge.
Apply to both sides.
Step 4: Fabric
Cut two small tabs of conductive fabric and place them on top of the protruding end of the conductive thread so that the tab half sticks to the stickytape and half sticks out.
Apply to both sides.
Cut three pieces of Velostat that are slightly smaller than the shape and size of your sensor. Stick one to either piece of stickytape and then prepare to stick both pieces of stickytape together and include the third piece of Velostat in between. If everything holds together, all is good.
Now you are finished. And can test it with a multimeter. Or see the last step in my Fabric Bend Sensor Instructable for information on how to hook your sensor up to your computer >> https://www.instructables.com/id/Fabric_bend_sensor/