Around half the size of a 1kg filament box, print two and it will be the same size as the filament box (at least the same size as the one that i use)

20.5 X 10.5 X 2 cm

my storage box had a bit of space left next the filament, (not big enough for another filament) so , desined this slim case to put the Silica Gel in it. maximizing the space usage in my dry box.

there is also a notch at the end, so it will latch close

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the walls are 2mm thick.
1mm think will also work, which will reduce the print time by 2 hours per piece. so for the top+bottom, it's a 4 hour saving!

the way that i did it, is to move it 1mm bellow the bed in cura.

but obviously it will be a bit more flimsy , also the top will not be flush on the box, since there will be 1mm missing on top, but not a major issue.

do not do this for PETG, since it will probably pop open , since it is more flexible.

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freecad 0.18 file also included