These are Hypercube 300 frame assembly tools.
Update: Now all printable on a 200x200mm printer!
The Frame Assembly Tool is for making the corners square and setting the parallel Y extrusions on the left and right sides of the frame.
The Z Rod Assembly Tool is for setting the distance of the front, upper and lower Z rod mounts accurately on the frame.
The Bed Frame Assembly Tool is use to build the print bed frame.
Note the latest files are different looking than what's in the videos but they work exactly the same.
I printed this using PLA at 75mm sec, 0.4mm nozzle at 225C, Bed at 60C. 3 perimeters, 3 top and 3 bottom layers.
I used AutoDesk Fusion 360