The foam is very siilar to cantact cement. Expect its verly liquid first and then "foams up" which should work very well with the kraftplex. If that doesn't work ill try the contact cement.
Costs:
hmm...
The materials for the undersuit alone about 250€
The materials für the cooling system 250€
The heads up dsiplay, electronics valves co2 system inclusive material I bought for figuring out the correct way.. ~600€
The material for the armor itself. paint, deatil parts 3D print material....1.2k€
With error marging and things I have to buy 2 times it surely sums up to about 3k.
If I calculate the time I spent and will be spending it is surely a 10k+ piece when finished, but the sentimental worth for me is much much higher (one reason for the excessive amount of time I spend and details I consider)
I also make other costumes which take much shorter
I attached one of my post-apocalyptic costumes for reference (3 day build):