Suggestions for plnfss

The following packages have something in common with the package plnfss. The packages are ordered in decreasing similarity.

Package ofs: Macros for managing large font collections
Package font-selection: Font selection for plain TeX
Package fontch: Changing fonts, sizes and encodings in Plain TeX
Package pdcmac: Damian Cugley’s document tools
Package settosize: Scale text to given width
Package varisize: Change font size in Plain TeX
Package old-fontch: Changing fonts, sizes and encodings in Plain TeX (obsolete version)
Package plain-cm: Variable sized fonts in Plain TeX
Package font-change: Macros to change text and mathematics fonts in plain TeX
Package unimath-plain-xetex: OpenType math support in (plain) XeTeX
Package font-change-xetex: Macros to change text and mathematics fonts in plain XeTeX
Package eplain: Extended plain TeX macros
Package harvmac: Macros for scientific articles
Package resumemac: Plain TeX macros for resumés
Package letter1: Letter formatting macros
Package mlawriter: Write MLA style documents in Plain TeX
Package graphics-pln: LaTeX-style graphics for Plain TeX users
Package histyle: A HighStyle environment for TeX
Package automagic: Automatic counter numbering in Plain TeX
Package lextex: Typesetting legal documents using plain TeX
Package plain-widow: Three output routines that extend \plainoutput
Package plain-grid: Four sets of macros for typesetting on a baseline grid
Package knst: Multiple-guess tests
Package optex: LuaTeX format based on Plain TeX and OPmac
Package ifis-macros: Check if a given input string is a number or dimension for TeX
Package letter-plain: Letter macros for Plain TeX
Package figplace: Floating figures in Plain TeX
Package lettermac: Simple macros for writing letters (Plain TeX)
Package label-pln: Print address labels in three columns
Package toc: Table of contents macros for Plain TeX
Package twoside: Two-side typesetting in Plain TeX