How to only get the symbol \Eins from mathbbol?

Question

I want to have a \mathbb{1} without affecting the usual appearance of \mathbb{R}.

I have tried the solutions given in https://tex.stackexchange.com/a/3493/8323 but the only that works is the \usepackage{mathbbol} (I suspect a package clash somewhere). But it affects all the other "blackboarded" characters.

Is it possible?

---

More precisions:

• When I say "it affects all the other "blackboarded" characters", I mean the font of the "blackboard" changes. But the thing is I don't want to change all the "blackboarded" character; I only want to add one.

• With other packages, it does not work: when I do \mathds{1} or \mathbbm{1} or, etc. the 1 is not doubled.

Apart from \usepackage{mathbbol}, the other packages I've tried are

\usepackage{dsfont}
\usepackage{bbm}
\usepackage{bbold}
\usepackage{mbboard}

Answer 1

It's quite simple if you want the symbol at its natural height.

\documentclass{article}
\usepackage{amsmath,amssymb}

\DeclareRobustCommand{\Eins}{%
  \text{\usefont{U}{bbold}{m}{n}1}%
}

\begin{document}

$\mathbb{A}\Eins$

\end{document}

You can get equal height with some more work.

\documentclass{article}
\usepackage{amsmath,amssymb}

\DeclareFontFamily{U}{bbold}{}
\DeclareFontShape{U}{bbold}{m}{n}
 {
  <-5.5> s*[1.069] bbold5
  <5.5-6.5> s*[1.069] bbold6
  <6.5-7.5> s*[1.069] bbold7
  <7.5-8.5> s*[1.069] bbold8
  <8.5-9.5> s*[1.069] bbold9
  <9.5-11> s*[1.069] bbold10
  <11-15> s*[1.069] bbold12
  <15-> s*[1.069] bbold17
 }{}

\DeclareRobustCommand{\Eins}{%
  \text{\usefont{U}{bbold}{m}{n}1}%
}

\begin{document}

$\mathbb{A}\Eins$

\end{document}