documentclass[tikz, border=5pt]{standalone}
    usepackage{tikz,pgfkeys}
    makeatletter
    defpgfutil@gobble#1{}
    pgfkeys{/handlers/.unknown to list/.code=%
      let#1pgfutil@gobble
      pgfkeysalso{% or pgfkeys{pgfkeyscurrentpath/.cd,
        .unknown/.code=% how to handle the difference between 'key' and 'key=value'?
          ifxpgfkeyscurrentvaluepgfkeysnovalue
            letpgfkeys@temppgfkeyscurrentname
          else
            expandafterexpandafterexpandafterdefexpandafterexpandafterexpandafterpgfkeys@tempexpandafterexpandafterexpandafter{expandafterpgfkeyscurrentnameexpandafter=expandafter{pgfkeyscurrentvalue}}%
          fi
          expandafterexpandafterexpandafterdefexpandafterexpandafterexpandafter#1expandafterexpandafterexpandafter{expandafter#1expandafter,pgfkeys@temp},%
         .@clear list/.code=let#1pgfutil@gobble}%
    }
    makeatother

    pgfkeys{
     /cuboid/.is family, /cuboid,
     depth/.estore in = cuboidz,
     width/.estore in = cuboidx,
     height/.estore in = cuboidy,
     front/.estore in = cuboidzStyle,
     side/.estore in = cuboidxStyle,
     top/.estore in = cuboidyStyle,
     .unknown to list = cuboidOptions,
     default/.style = {width=1, height=1, depth=1, front=, side=, top=, draw},
    }

    newcommand{cuboid}[2][]{
      pgfkeys{/cuboid, default, #1}%
      begingroup
        edefx{%
          endgroup
          noexpandbegin{scope}[shift={#2}, join=bevel, cuboidOptions]
            noexpanddraw[fill,cuboidyStyle] (0,cuboidy,0) -- (cuboidx,cuboidy,0) -- (cuboidx,cuboidy,cuboidz) -- (0,cuboidy,cuboidz) -- cycle;
            noexpanddraw[fill,cuboidxStyle] (cuboidx,0,0) -- (cuboidx,cuboidy,0) -- (cuboidx,cuboidy,cuboidz) -- (cuboidx,0,cuboidz) -- cycle;
            noexpanddraw[fill,cuboidzStyle] (0,0,cuboidz) -- (cuboidx,0,cuboidz) -- (cuboidx,cuboidy,cuboidz) -- (0,cuboidy,cuboidz) -- cycle;
          noexpandend{scope}
          noexpandpgfkeys{/cuboid/.@clear list}
        }%
        x
    }

    begin{document}
    tikzstyle{interior}=[fill=blue!50]
    begin{tikzpicture}[scale=.7, fill=blue!60, z={(225:.8)}, x={(-10:1)}]
      cuboid[front=interior, side=interior]{(0,1.5,0)} cuboid[front=interior, width=2]{(1.25,1.5,0)}
      cuboid[side=interior]{(0,1.5,1.5)} cuboid[width=2, front=]{(1.25,1.5,1.5)}
    end{tikzpicture}
    end{document}