Is it possible to make clone of http://www.makerbeam.eu/ of some easy accessible material like:
Using any type of CNC machine to mill some holes and rails in those materials may give sufficient results e.g. to make a prototype of 3D printer of such "beams".
Of course it won't be as rigid and durable but for making prototypes it may be good idea.
Just for reference: when reading this http://www.lowtechmagazine.com/2012/12/how-to-make-everything-ourselves-open-modular-hardware.html I've found this http://bitbeam.org/, this https://www.google.com/search?q=grid+beam&client=ubuntu&hs=zAr&channel=fs&source=lnms&tbm=isch&sa=X&ved=0CAcQ_AUoAWoVChMIiLHdqf2MyQIVQZoUCh1cHwV1&biw=1215&bih=927 and this http://www.gridbeam.com/, and this https://www.tetrixrobotics.com/.