How would you improve slab boxes? aka another project for my 3D printer

Not a bad idea. I don’t have my slabs in plastic sleeves, though I suppose I could use some of the slab-sized ziplock poly bags I have (just dunno if I have enough).

So far I haven’t done that, and the slabs are naked in the divider-less boxes. When they’re in the safe deposit drawers. But they don’t get moved around much, because the boxes only come out of safe deposit a couple times a year and don’t get moved around much.

When I do travel with my coins, I have two aluminum 100-slab briefcases with carrying handles and foam dividers.

 

My travel briefcases are similar to that, except they have carrying handles and foam dividers (notches) between each slab slot. They will fit any standard sized slab (even the thick PCGS/NGC, because the foam notches “give” a little bit). Old small ANACS would be loose in there. But I no longer own any of those anyway.

 

If those are the same height and width as a standard slab (only a bit thicker), then yes, I think they should fit, albeit pretty snugly. I have a couple of thick PCGS slabs that go into those carry cases with the foam notches. Gotta push ‘em down rather firmly at first, but they go in OK.

Edit: oh, wait- you showed a pic of a five-ounce coin. That’s more than just a thick slab- it’s an oversized slab. Oversized won’t fit, because… well… they’re oversized. But there are some PCGS slabs with the usual dimensions- normal height and width, but extra thickness. Those will fit.