[CentOS] Query on make

Greetings,

I have created several scripts which needs to be packaged.

I have done my groundwork on rpmbuild

Let us say I have 4 directories with scripts in them
dir1, dir2, dir3 and dir4

I want to create different packages which will contain the compiled
code (err.. shc)
pack1: dir1,dir2
pack2: dir1,dir3
pack3: dir1,dir3

I want the resulting rpm packages will be residing elsewhere (perhaps
BUILDROOT).

Now I am aware of using different specfiles

But When and how do I compile the packages?

Using makefiles? Can it produce different variants?

I am a bit confused as  to the workflow.

the sources cannot be part of eithr the srpm or the deliverable rpms.

Please note that this project will be maintained by someone else with
unknown familiarity.

Any suggestions, pointers, help etc. please?

Thanks in advance

-- 
Regards,

Rajagopal