Totally new user, been to essentials and surfaceing training so far. what I got is a small foam part with a push pin  what i need is a nest that the part fits into at max tolerance if it fits in its good then a seperate block with a bushing to slide over bushing to check location. What i have tried so far is the combine function by extrudeing a box then subtracting. Problem is to split block i cant just do this in the center or any flat plane as the part moves up and down all over. i understand this may be hard to visualize. what i would do in old software was offset side walls max tolerance  and extended bottom and sides and trimmed to fill gap between them then ruled surface from top  to make a block. any better ways to do this that is less time consuming than modifiying every surface like this