There are numerous reliable ways to straighten a warped PBT spacebar, ranging from using
boiling water to heat guns to
using the heated bed of a budget 3D printer.
The process seems straightforward:
1.) Heat up the spacebar to about 90° C.
2.) Hold the spacebar down against a flat surface, using weights, some sort of clamp, or just your hands.
3.) Let the spacebar cool down slowly back to room temperature.
An industrial tool to straighten a bunch of spacebars at once would be pretty straightforward to make - you get two straight and flat hunks of metal, put a bunch of spacebars in between them, clamp the two pieces together, and put it in an oven (or install cartridge heaters into the hunks of metal), heat it up, and let it cool back down. Yet, ePBT and (to a lesser extent) Infinikey still ship warped spacebars. My ePBT Royal Alpha set had some very warped spacebars (that were thankfully easily fixed using Maarten's 3D-printer method). Why in 2020 is still an issue?