Answer : To give you a start.   \documentclass[tikz,border=3mm]{standalone} \usetikzlibrary{perspective} \begin{document} \begin{tikzpicture}[3d view={30}{15},line cap=round,     declare function={ax=2;ay=1.5;az=2.5;bx=0.5;bz=0.5;}]   \draw (0,0,0) -- (ax,0,0) -- (ax,0,bz) -- (bx,0,bz) -- (bx,0,az)   -- (0,0,az) -- cycle    (0,0,az) -- (0,ay,az) -- (bx,ay,az) edge ++ (0,-ay,0)   -- (bx,ay,az) edge ++ (0,-ay,0)   -- (bx,ay,bz) edge ++ (0,-ay,0)    -- (ax,ay,bz) edge ++ (0,-ay,0)   -- (ax,ay,0) -- (ax,0,0); \end{tikzpicture} \end{document}     The perspective  library allows us to change the view angles, and declare function  is used to define parameters that can be changed, too.   \documentclass[tikz,border=3mm]{standalone} \usetikzlibrary{perspective} \begin{document} \begin{tikzpicture}[3d view={40}{35},line cap=round,     declare function={ax=3;ay=2;az=2.5;bx=0.8;bz=0.8;}]   \draw (0,0,0) -- (ax,0,0) -- (ax,0,bz) -- (bx,0,bz) -- (bx,0,az)   -- (0,0,az) -- cycle    (0,0,az) -- (0,a...