DIY tensile strength testing I want to tackle an experiment with the following goal:


  Determine the correlations between printing parameters (temperatures,
  speeds, humidity, perimeters, infill, etc.) and tensile strength using
  a specific 3D printer, test specimen, and filament brand/model.


This goal calls for two parts then: a standardized test procedure and test specimen. For the test procedure, I've been asking myself:


  What portable, measurable and roughly consistent tensile strength test
  does not require building a complicated machine, can be performed with
  ready-made tools or machines available at a large hardware store, and
  can be set up within 5 minutes?


I am thinking here about a procedure that lies somewhere between this hanging scale test and ISO 527. Definitely not using bare hands or pliers. Once the procedure is defined, this begs the question:


  Is the ISO 3167 multipurpose test specimen an appropriate specimen for
  the test procedure outlined above or are there other specimens that
  are more suitable?


I was thinking that, since the usual filaments have an ultimate strength of around 40-60 MPa, perhaps the "recoil" would be too much and one needs to use a smaller, weaker specimen.
For these kind of tests you could rely on the ASTM standards. They define test procedures and test specimen sizes for different types of tests. Or you can derive a specimen yourself based on these standards (e.g. for my bachelor's degree I used an alternative notch impact specimen as I was bound to the amount of available material of the turbine rotor blade the specimens were taken from). Considering the material, you could device up a contraption made from extrusion profiles or something.

Please do note that to get reasonable results, you would have to do a lot of tests as the spread in results is probably even more than in metals. 

The company I work for does this, these material qualification programmes run for long times (years, as we also do fatigue and creep testing), and a lot of samples are tested to qualify for use in Aerospace applications.