Hi, I recently Traveled from Siouth Africa to Australia with my iMac 21' as hand luggage with Qantas. The reason I am posting this is because prior to my departure I could find very little info or people that have done this. I decided that the original I mac packaging was far too big and bulky to take as hand luggage. So I went to the local box supply store and purchased some double wall pieces of card board. Unfortunatly I don't have pics of the boards but the were about 1.5m X 0.7m and I had four. I went for a matchbox style box as you need to take the computer out of the box at the security scan points, the box allowed the mac to be exposed but still protected in a 'cup' of cardboard and bubble wrap. As you can see the new box made it into the hand luggage bin and was dead on 7kg which was within allowance for Qantas. Once it was inside the storage area above the seats there was plenty of space and the box could have acualy been a bit larger. The dimensions of the box are length across - 56cm width bottom - 20cm width top - 6cm height - 53cm Its important to note that these dimensions are for the 'external' match box piece the internal match box piece slid into it nice and snuggly. I bought some nylon strapping which i sewed together around the box swell. If you are going to try this just be careful when handling the box as it will slide out if it is tilted at an angle. So it is possible to travel with the IMac 21' as hand luggage. I also carried my camera bag which weighed 8kg and I had no issues ( I did dent ask at the check in if I was allowed to take two items as hand luggage, because it then gives them a reason to tell you its not allowed.) I wrapped everything in a few layers of bubble wrap too which was super important to absorb the vibrations and impacts. I hope you find this helpful.