This is based on the Clas Ohlson instrument case - code 38-3978. Note that this is leaving their product line - but is being replaced by Clas Ohlson instrument case - code 38-5920 - which looks identical - is cheaper - and I've still not ever found it in stock in any of the shops. In the end I got fed up waiting.
Foam layout showing the lowest layer of packing.
Back left you can see the Hubsan x4 FPV. Around it you can see support foam so that the radio can go on top.
Back right - batteries and charger for the Blade QX nano.
Forward left - the area for all other batteries, chargers, spare propellers etc.
Forward right - the Blade QX nano itself.
Foam layout showing the lowest layer of packing
Now we can add the radios:
Hubsan x4 FPV on top of the Hubsan x4 itself (hence the spacers around it).
Blade QX Nano radio (RTF variant) back right.
Radio for the el-cheapo UFO from deal extreme middle front.
Foam layout showing the second layer of packing
Now we can add the last quad:
El-cheapo UFO from deal extreme front right. Underneath - protecting the Blade QX Nano - some loose foam from where we took some out to make space for things.
Foam layout showing the third layer of packing
Finally the last foam bits go in - covering the battery/charger area and a small piece to keep the el-cheapo quad from moving around too much.