Tension samples use M6 threads on both uses. Designed for anyone to make custom sample holders. Please print sample holders out of the strongest material available. I used PA6, but i have also ordered MJF Steel sample piece holders.

Print sample piece in the following orientation.

Sample piece can be only be scaled down in one direction if stronger materials are used (like SLS samples)

I do not currently have a load cell installed, but i suggest using a load cell that looks like the following (rated for 50kg+)

You can also design your own adapter for a commercial force gauge (set on peak mode)

Hardware: 

400mm 2020 Aluminum extrusion x4
Nema17 stepper motor x1
[Stepper motor controller with PSU] x1 (although motor does not need to be powered. Gears can be spun manually.)
T8 lead screw with round brass adapter x2
Assortment of m3 hex set machine screws + nuts
Bearing 42mm OD, 20mm ID, 12mm Height x4

Print parts to be as strong as possible. I printed all of it from a combination of ABS (pink), and ASA (white). Beige parts are PA6 nylon.

Hammer in aluminum extrusion, and use epoxy glue for connecting the lead screw to the large gear and bearing adapter

Use 3d printer lubricant for the lead screw (as well as some on the gears and aluminum extrusion, where the mover touches)

If the sample doesn't break (especially with stronger filaments) adjust standardized sample thickness.