I saw a nice spare part storage / transport box at a ex-army dump which was used for storing and transporting a Leopard 1 firing system spare part. But I had immediately a target for it in mind.
The box was initial filled with nice craft-able hard foam (more then 90% of the box content in 2 pieces) so I could re-use it and cut it into almost any desirable shape.
A waterproof field day box for my FT-817 and a basic set of materials.
Don't let the picture's foul you, the box is just 23x20x20cm.
Content :
1 x Yaesu FT-817
1 x 6m Coax
2 x 10m rope
1 x 20/40m endfed wire (with coil)
1 x 6m/2m/70cm antenna
1 x hand mike
And still some room for additional stuff.