I started the ground work for making an A4 origami envelope pkg to support this origami folding technique, which I previously mentioned here. This is my code so far:

\documentclass[paper=a4, DIV=34, footinclude=false, firstfoot=false]{scrreprt}

\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc} % suggested to avoid ``OT1 encoding''
\usepackage[fontsize=12.2pt]{fontsize} % furnishes \changefontsize but tampers with picture environment coordinate positions!
\usepackage[grid, gridunit=mm, gridcolor=blue!40, subgridcolor=blue!20]{eso-pic}  % Makes a grid covering the whole page
\usepackage{graphpap}
\usepackage{overpic} % needed for rotatebox (WTF?)
\usepackage{ocgx2}    % furnishes the ocg environment
\usepackage{nopageno} % suppress page numbering (because pagenumber=false doesn't work)
\usepackage{fancybox}
\usepackage{lipsum}

\begin{document}

\setlength{\unitlength}{1mm}
\begin{ocg}{fold marks}{fm1}{on}\color{red}
  \begin{picture}(0,0)
    \put(136,7){\setlength{\fboxsep}{0pt}\fbox{\rule{0.2pt}{1ex}}}
    \put(94,-136){\setlength{\fboxsep}{0pt}\fbox{\rule{1ex}{0.2pt}}}
    \put(188,-136){\setlength{\fboxsep}{0pt}\fbox{\rule{1ex}{0.2pt}}}
  \end{picture}
\end{ocg}%

\lipsum

\newpage

\rotatebox{-45}{%
  \setlength{\unitlength}{1mm}
  \begin{picture}(106,155)(-30,35)
    \begin{ocg}{gridlines}{grid}{off}
      \graphpaper[5](0,0)(105,155)
      \put(105,0){X\textsuperscript{max}}
      \put(0,155){Y\textsuperscript{max}}
      \put(105,155){XY\textsuperscript{max}}
    \end{ocg}
    \begin{ocg}{region boundaries}{rb}{on}
      \put(25,0){\color{blue}\thicklines\line(-1,1){25}}% line bisecting the leftmost square to mark off a small triangle that wraps to the other side
      \put(-16,0){\color{blue}\rule{41mm}{2pt}}
      \put(-20,25){\rotatebox{-135}{\color{blue}\rule{28mm}{2pt}}}
      \put(105,130){\color{magenta}\thicklines\line(-1,1){25}}% line bisecting the rightmost square to mark off a small triangle that wraps to the other side
      \put(80,155){\color{magenta}\rule{41mm}{2pt}}
      \put(105,150){\rotatebox{-135}{\color{magenta}\rule{28mm}{2pt}}}
      \put(0,25){\color{cyan}\thicklines\line(-1,1){98}}% big triangle, LHS, longest (hypotenuse) edge - which splits the backside diagonally
      \put(-75,150){\color{cyan}\rule{75mm}{2pt}}
      \put(100,0){\color{green}\rule{75mm}{2pt}}% big triangle, RHS, edge nearest the page bottom
      \put(105,130){\color{green}\line(1,-1){98}}% big triangle, RHS, longest (hypotenuse) edge - which splits the backside diagonally
    \end{ocg}
    \begin{ocg}{region labels}{rl}{on}
      \put(-80,80){\Huge\rotatebox{-45}{\ovalbox{concealed}}}
      \put(150,70){\Huge\rotatebox{135}{\ovalbox{concealed}}}
      \put(0,190){\Huge\rotatebox{0}{\ovalbox{concealed}}}
      \put(50,-50){\Huge\rotatebox{0}{\ovalbox{concealed}}}
      \put(50,50){\Huge\rotatebox{90}{\ovalbox{Top/Front}}}
      \put(100,20){\Huge\rotatebox{135}{\ovalbox{Bottom/Back RHS Triangle}}}   % RHS: right-hand side
      \put(-100,130){\Huge\rotatebox{-45}{\ovalbox{Bottom/Back LHS Triangle}}} % LHS: left-hand side
      \put(-20,2){\small\rotatebox{0}{\ovalbox{Backside tiny triangle}}}       % LHS: left-hand side
      \put(85,152){\small\rotatebox{180}{\ovalbox{Backside tiny triangle}}}       % RHS: left-hand side
    \end{ocg}
  \end{picture}
}
\end{document}

It works for me, as long as I use KOMAscript with a DIV setting of “34” and retain the fontsize package. This code is not suitable for packaging, for the general public, because the coordinates are fragile. Most people would not want to be constrained to the KOMAscript family of doc classes. Why the strange side-effects? Why aren’t the position instructions absolute?