He hecho esto hasta ahora pero no puedo agregar esas esferas o cubos debajo del cuadro TikZ y escribir dentro de ellos. Además no pude crear las flechas.
\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}
Esto es lo que estoy tratando de conseguir.
