PCB testing fixture

###A "3rd-hand" style PCB and testprobes holder for testing, debugging electronics.

###This setup has shown quite useful to steadily hold oscilloscope and extra probes to PCBs during development, freeing both hands for more interesting tasks than just holding a probe.
Some details of the construction:

* The metal articulated-arm was taken from a cheap dial-gauge. The base was unscrewed and the M5 bolt is attached to the aluminum profile using an M5 T-nut. This arm is quite nice to use, since allows you to hold the scope probe in different angles and keep it steady, even when the ground-spring is attached to the tip for low-noise or high-speed measurements...
* The aluminum profile is a 20x20mm from openbuilds, cut to approx. 20cm.
* For holding the PCB, one side is held in place with an M3 bolt, while the other is free to move across the rail, spring-loaded by a ~50mm long spring which fits inside the profile and is held by another T-nut.
* The 3D printed 2nd arm uses also