I started playing with the Lego bottom greebles. This is as far as I got on the plane flight back, it goes from about omniwheel to omniwheel (a bit further actually), but misses edges.
Apparently all 4 sides are the same, which I confirmed, although the one at Celebration has damaged bits on the front and rear (and probably other places).
The bricks are cut for the Omniwheels. I've decided to leave those as voids rather than have partial bricks. I don't think the partical bits that are cut are that interesting, and it seems easier if it didn't have to be cut... We could make it so we had to cut them, but I don't know what the missing bits would look like if there weren't omniwheels (since they're missing).
As mentioned, it is 4 identical pieces. It looks like they've been cut @ about 45 degrees on the corners, however they don't seem to line up completely. Not sure if they had to be trimmed smaller or just wasn't important to get a "perfect" cut.
I also don't have a lot of detail around the corners. If someone else has pix I'll take a look, however it gets pretty muddy anyway when the bricks run into the corner spheres/faux wheels. Like stuff was cut & glued and puttied to fit. Nobody can see that soe I'm not too worried about it. Probably any mold should have a void for the faux wheels?
FWIW, my mockup attempts to keep the seams of the original bricks. Right now it's rough and wouldn't fit together well. It would be easier to build (& stronger in Lego) if some of those were oriented differently, but I assume folks would like to have the original marks/lines between the bricks, so that's what I'm going with for now - besides if it's cast and molded that's less interesting.
This is the same picture, however a few bricks are red where they are obscured in my reference photos. Probably about 85% chance each of those is "correct", though there are alternatives that would fit the photo just as well. Eg: a tile might continue behind a brick or it might stop and leave a bare stud, etc. Nothing major, very minor details. I might get closer when I check other pictures.
The blue bits are ones that might need removed for the omniwheel void, they are cut in the reference, but I thought they might be complete, but they may need cut.
The corners need work, though there isn't really that much missing. This is ~450 bricks, but I didn't make the back wall the original has, and the original might be solid. So we're looking at something like 2000 bricks+ for a brick-built complete build. Lara will probably figure out how to lighten that some for her build.