This is an insert for the Marvel United board game and expansions. It fits in two of the larger boxes (it doesn't fit in the smaller expansion boxes - I use the original Marvel United box and the X-Men base game box). Using this insert I've been able to condense the following with sleeved cards and a little room to spare:
I imagine it would work equally well with other combinations of expansions. Note that I use the segmented card trays for the villains, one per segment, and put the heroes all together in the unsegmented card trays - mix and match as desired. The location tray is also split to accommodate smaller printers (I have an A1 Mini).