What LEGO set has the smallest box? Similar to What Lego set has the biggest box? but probably more-challenging to answer, what LEGO set has the smallest box (either square or cubic dimensions work)?

I'm talking actual sets with an item number and an actual boxes, not polybags or sub-components in a set (like a minifig cape box).
I thought that promotional boxed sets were good candidates for the smallest box as well, as I own a 1630-1 Helicopter (which, incidentally, I got as a promotional gift for buying toothpaste at some point in the 90s IIRC), at 7 x 7 x 4.5 cm (220cm3/0.22 litres).
There are sets with similar dimensions as well, such as 5018-1 Gravity Games Promotional Set at 7 x 7.5 x 4 cm (210cm3/0.21 litres), 7912-1 Helicopter Promotional (Duracell), 5017-1 Hockey Promotional set. and some others.
I thought those were the smallest in volume, but after a deeper search on bricklink I came up with a thinner 2.5cm (281-1 1 x 2 and 3 x 2 Sloping Bricks, Red with 8.6 x 6.2 x 2.5 cm / 133cm3/0.133 litres):

And after delving in the sets with a low part cound, I came up with an even thinner 1.8cm box with 1222-2 1x1 round bricks, at 7.5 x 5.5 x 1.8 cm (74.25cm3/0.074 litres) (same box size as 1241-2, 1240-2, 1230-2 and possibly others):

Also of note are the 1:87-scale cars from the 60s, like e.g. 265-2 1:87 Karmann Ghia with Garage:

The &quot;box&quot; itself is a transparent hollow brick, specifically part number 721, 4x8 studs wide by 3 bricks high wrapped in a paper strip, which puts it at 3.2cm x 6.4cm x 3.04cm or 62.25cm3/0.062 litres. (Hey, you asked for the smallest box, not the smallest cardboard box!)
Apparently some of these 1:87-scale cars, e.g. 671-3 1:87 Vauxhall Victor Estate with Garage were sold with an actual cardboard box around them, with listed dimensions of 3.2 x 3.2 x 6.5cm (66.56cm3/0.066 litres):