I use a marine battery box, see picture below.
I don't recall the size offhand, but it is big enough for the Autoformer with room to coil up the cord and one of the yellow stacking "lego blocks"
I do not use the top cap.
Works good for carrying and storing the Autoformer and when I use it I put the Autoformer on the the yellow lego block and then cover it with the battery box.
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