You don't have to actually copypaste. You can use CMake and FetchContent/CPM. You can specify custom build commands or inline declare a project for anything small that you pull in that doesn't use CMake (you can call add_library with a glob on the folder FetchContent pulled in, for example - I've done so here https://github.com/basis-robotics/basis/blob/main/cpp/CMakeL... for a header only lib). For large external dependencies that are either very slow to compile or for some reason aren't CMake, reach for the system package manager or similar. If you want to be really cross platform and are supporting Qt/wxwidgets/etc, vcpkg+CMake+clang is solid combo, if a bit slow and a bit disk space heavy with the build cache.