So again for "1000 - 1400 chips" you should use the 4800 Apache case, they are amazing with a ton of room for extras. The bad news is that the depth of the case is not perfect. If you pluck out the two layers with no additional support it will leave your top rack of chips sitting below flush. The Home Depot and other hardware stores sell sheets of foam typically in the HVAC section. Here is what I do.
1) take out the two sheets of pluck foam, find "close cell" foam board between 3/4" to 1" thick and cut it to the dimensions of your case (I use a sheet of fiber glass over top but you can just use the foam)
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2) next take one of the two sheets of pluck foam using a fillet knife or other long sharp blade you cut one of those sheets perfectly in half, now you can pluck out your desired configuration.
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I put the cut sheet face down below the full sheet, this corrects the height issue and allows the top rack to press into the lid foam correctly and holds all of your chips in place
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If your chips are not sitting above the lip of the bottom half then they will not press into the Lid foam and they will not be held in place... when you open the case you are going to have a mess., 1/2" to 3/4" above is perfect.
Now that configuration is only 5 rows of double stacks or 1000 chips. To get to 12 - 1400 you also have to pluck out the lower section.
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That first case has 1000 chips, technically I prefer having the chips start in the top left of the case but that foam was from a previous set up so I went with what I had. The third case is holding 1,800 (triple stacked not double) but that would be the orientation for 1,200 chips, the second case has 2,100 chips (triple stacked) but that would be the orientation for 1,400 double stacked with the foam beneath. 4th case has 1,400 chips with the foam.
You can really do whatever layout you want, this is just what works for us.
Hope that helps.
Ben