Blue SG90 mini robot arm

Here is a small video of a [demo run](https://youtu.be/-Atkwzk3qv4) of the robot arm.

The Arduino UNO program can be downloaded from [github](https://github.com/refob/RobotDemo).

Bill of material
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* 4x Servo SG90
* 1x Hex Socket Head Cap Screw M2x10 DIN 912
* 1x Button Head Screw Flanged M2.5x25 ISO 7380-2
* 3x Hex Socket Head Cap Screw M2.5x20 DIN 912
* 1x Hex Socket Head Cap Screw M2.5x15 DIN 912
* 8x Hex Socket Head Cap Screw M2.5x8 DIN 912
* 2x Hex Socket Head Cap Screw M3x10 DIN 912
* 1x Hex Nut M2 DIN 934
* 2x Hex Nut M2.5 DIN 934
* 4x Self Locking Nut M2.5 DIN982
* 2x countersunk head tapping screw 2.2x6 DIN 7982
* 1x countersunk head tapping screw 2.2x8 DIN 7982
* 6x metal balls with 4mm diameter