Um...
That wouldn't exactly be how you would work on the suit...
You see, it's actually made using a venom symbiote
And the collector doesn't leave it lying around either, it's contained within the crystal of creation
So maybe he got his hands on a late prototype of the symbiote and used that to make the armor
It could definitely enter a solid state without a person in it if it has something to grab on to such as a mannequin