This question has been cross-posted to [tex.stackexchange.com](https://tex.stackexchange.com/q/752610/2288).

I would like to know how to properly define a custom style key `topstyle` inside the family `my cylinder parameters` and apply it to any pic instance.

The following produces the error 

> Package xcolor Error: Undefined color `fill=red'

```
\documentclass[border=10pt]{standalone}
\usepackage{tikz}
\usepackage{tikz-3dplot}

\tikzset{
	my cylinder parameters/.is family,
	my cylinder parameters,
	radius/.store in = \cylRadius, radius=1,
	height/.store in = \cylHeight, height=2,
	rotation/.store in = \cylRotation, rotation=0,
	color/.store in = \cylColor, color=blue,
	topstyle/.store in = \cylTopStyle,
	topstyle = {fill=\cylColor!20, fill opacity=0.1},
	topstyle/.default = {fill=\cylColor!20, fill opacity=0.1},
}

\tikzset{
	pics/mycylinder/.style = {
		code = {
			\tikzset{my cylinder parameters, #1}
			\tikzset{/my cylinder parameters/.cd}
			
			\begin{scope}[tdplot_main_coords]				
				\draw[thick, \cylTopStyle] (0,0,\cylHeight) circle(\cylRadius);
			\end{scope}
		}
	}
}

\begin{document}
	
	\newcommand{\rotX}{60}
	\newcommand{\rotZ}{40}
	
	\tdplotsetmaincoords{\rotX}{\rotZ}
	
	\begin{tikzpicture}[tdplot_main_coords]
		\pic at (2,0,0) {mycylinder={color=red}};
		\pic at (0,0,0) {mycylinder={color=red, topstyle}};
		\pic at (-2,0,0) {mycylinder={color=red, topstyle = {fill=green}}};
	\end{tikzpicture}
\end{document}
```