Haha, yes it is a dangerous job! I made a hoop template and then worked to that, on the floor using my knee to pin things down so wire didn’t fly about!
I will say after this windy and wet winter that 4mm wire didn’t work for me, they bent out of shape and fell over in the wind and under weight of rain
i will try next year with 5mm or even 6mm. 6mm will be hard to bend, but worth the work i think
Perhaps with 4mm you will want to double the amount of hoops in the bed (every 1/2 metre) to provide extra strength, and stick the wire in the ground for 1ft at least, possibly more – but i found the 4mm wire bent at the ground