How make yourself a pressure sensor

The goal is to be able to obtain a pressure sensor capable of giving a resistance change.

Get duct tape. Make a square 12 x 12 cm. Cut four Velostat sheets of size 10 x 10 cm.
Take the copper wire diameter of 0.75 and carries a spiral diameter of 10 cm. Look at the picture.

Do the same thing with another duct tape

Get a Velostat sheet and lay it on the fabric tape in such a way that sticking and it rests on the copper wire. Repeat this action on the other side.

Take two other sheets of 10x10 cm and Velostat move between the two faces so as to create a sandwich. It will have a total of 4 sheets of overlapping Velostat.
Press and glue the two surfaces carefully .
With a digital meter you can measure a resistance of about 3 Kohm when there is no pressure. If siu press you will notice a decrease in resistance.

This is the final product. These sensors have been used in the project Kumite Electronic speed game to measure the pressure of the punches with karate techniques.
To measure the resistance change has been connected the pressure sensor in series with a resistance of 3.3 Kohm so as to obtain a variation of the analog signal connected to an input (A0) of Arduino UNO.