I´ve seen Achatz in the netherlands are using TRESPA for their Prusa i3 frames
I searched a little and also found a source for alu-PP-alu sandwich plates ( used for traffic signs etc. ) which is much cheaper.
German site
The size is 3mm thick with 0.3mm alu sheet laminations on both sides.
Would it make a good replacement for my acrylic y-bed carrier?
Could we even make a complete frame out off it?
-Olaf