After you clone the repo and install the project dependencies, you should prepare the build setup by running the following command only for the first time:
npm run init-build
This will build and link all the packages.
Use the following command to build each package separately
npm run build-core
npm run build-lightbox
npm run build-gallerize
NOTE: These commands will not set the version in package.json, but they run faster while developing
Use the following command to build all packages
npm run build-all
Test your changes then submit your PR