how do i keep my initial values intact and locked and pile up based on that values (Random piling )

roshankarel

So i am creating pile of ram, cpu, and may be some other computer parts  material in substance designer and i am having an issue with piling things i used tile sampler and randomised the input now the problem is this   the pieces should overlap each other not change its value and mix up with each other
so how do i keep my initial values intact and locked and pile up based on that values 

poopipe

Tile sampler colour lets you use alpha to mask things off

If you want to pile stuff up you probably want to try several shape splatters in series