There are two problems with makeself port.
1. Starting from version 2.x makeself binary consists of two scripts - makeself.sh and makeself-header.sh. The port was updated recently, but file makeself-header.sh was not added to port.
2. The makeself script is not compatible with FreeBSD's /bin/sh. It produces broken archives when runs under /bin/sh. Changing interpreter to bash resolves this problem.
Fix: The following patch resolves both of these problems.
How-To-Repeat: Problem 1. Install makeself from the ports collection and try to run it. It will fail and will report that the makeself-header.sh file is missing.
Problem 2. Copy makeself-header.sh to /usr/local/bin/ to avoid first problem, create the self-extracting archive with the makeself then try to run that archive. Self-extractor will fail and will complain about checksum error.