TikZ 框內的 3D 形狀和文字

Question

到目前為止我已經做到了，但我無法在 TikZ 框下添加這些球體或立方體並在其中寫入。我也無法創建箭頭。

\documentclass[ border=1cm]{standalone}
\usepackage[table,xcdraw,dvipsnames,svgnames,x11names]{xcolor}\usepackage{tikz}
\usetikzlibrary{shapes,shadows,arrows.meta,decorations.pathmorphing,
    backgrounds,
    fit,fadings,
    matrix,
    positioning,
    quotes}

\begin{document}
\begin{tikzpicture}
\node[rectangle,align=center,fill=Green,text=white,minimum width=2.5cm,text width=4cm] (A) at (0,0) {Nanomaterial\\Fabrication Methods};
\node[ellipse,draw=red,minimum width=9cm,minimum height=7cm] (B) at (0,0) {};
\node[rectangle,draw=Blue3,minimum width=2.5cm,minimum height=2cm,fill=Grey!20] (C) at (30:4.5) {};
\node[rectangle,draw=Blue3,minimum width=2.5cm,minimum height=2cm,fill=Gray!20] (D) at (90:3.5) {};
\node[rectangle,draw=Blue3,minimum width=2.5cm,minimum height=2cm,fill=Gray!20] (E) at (150:4.5) {};
\node[rectangle,draw=Blue3,minimum width=2.5cm,minimum height=2cm,fill=Gray!20] (F) at (220:4) {};
\node[rectangle,draw=Blue3,minimum width=2.5cm,minimum height=2cm,fill=Gray!20] (G) at (-40:4) {};
\node [rectangle,fill=Blue3,minimum width=2.5cm,text=white,minimum height=1.1cm, left=10mm of F,yshift=2cm] (5) {Bottom up};
\node [rectangle,fill=Blue3,minimum width=2.5cm,text=white,minimum height=1.1cm, above=2mm of C,xshift=2cm] (6) {Top down};

\end{tikzpicture}
\end{document}

這就是我想要得到的。