Concave Ti4 Frame

This is a modified version of the frame used in https://makerworld.com/en/models/1993497-twilight-imperium-4-galaxy-frame-and-raised-stand#profileId-2145557Instead of being a tiered frame up to mecatol it instead concaves down to mecatol. While I personally haven't printed it (I like the tiered version) adjusting the parameters was simple enough and shouldn't cause any problem for printing. It should work fine with the base supplied in the original project.It has a shorter 7.5mm step since i felt that the sinking could hide things easier. So the effect is slightly more subtle.