Cheapest way to do it is to get a Peli 1510 which will house 2 machines & 3 PSU, then carry the 3rd in the smallest hand/shoulder case you can find. No outer pockets or anything, it needs to seen as an accessory! I’ve got away with this hundreds of times with KLM, Emirates & Etihad.
Only Ryan air stopped me over the Peli. Those cheeky bastards have reduced the size allowance by something like 4mm to purposely catch people out who’ve bought cases within the guidelines! I had to check it at the gate but got away with being charged
Also keep the Peli out of sight as much as possible when checking regular luggage. Even though it’s designed as hand luggage, with 2 machines in there it could be over weight on some airlines.
You can get larger Peli’s that will fit 3 machines if you do want to check it but I’m guessing not!
Edit. Re MK7 post, yeah be prepared for the occasional swab test, no biggy though. Also, I’ve heard people talk about having to display the equipment working, I’ve never encountered this, not in 250+ flights Worldwide!