I have been doing some serious days work packing my three garages into a 20' shipping container. I was fortunate and got a number of steel office filing cabinets which are just the bees' knees as the drawer slides are sturdy and the drawers easily hold a number of items such as electrical hand tools etc etc.
So far, Lego, 3 filing cabinets filled with electrical and computer antiques, my collection of various electric motors up to 5 hp, my ships radar scanner, a huge collection of electrical meters (mostly very old and some big), 60 drawer steel cabinet filled with workshop bits such as nuts, bolts, screws, more antique electrical bits. Several cartons of radio valves ('toobes') and all manner of interesting bits and bobs. 4 more filing cabinets empty but already in the box for last minute items.
Still to go, lathe, cold saw, bandsaw, drill presses, compressor, mig welder, arc welder, Benelli, Honda and Douglas motor bikes.
I think it will all fit OK but it already weighs over 7 tonnes! I was trying to keep below 6 for the cheapest freight rate but no show of doing that!

Incidently, while doing this project I un-covered my audio cassette collection of a few hundred tapes, I was about to dump them all but a test play of a few of them show they have survived very well so they are in the box too.