How to get the lowercase calligraphic symbols?

Three fonts have lowercase calligraphic letters and a bold version, and a LaTeX package to use them:

• bickham adapted for LaTeX from Adobe's Bickham Script Pro opentype font,
• boondox (with a variant boondox-o) (adapted from the BOONDOXCalligraphic STIX font),
• dutchcal adapted from ESSTIX math calligraphic font.

In addition the mathabx package has a mathc calligraphic font (in version normal only), but I couldn't make it work.

Here a demo:

        \documentclass[12pt]{article}
        \usepackage[utf8]{inputenc}

        %\usepackage{bickham}
        \usepackage{boondox-cal}
        %\usepackage{boondox-calo}
       % \usepackage{dutchcal}

        \pagestyle{empty}

        \begin{document}%
        \textbf{%
        % Bickham
        Boondox :
        % Boondox-o
        % Dutchcal
        }%

        \[ \begin{array}[t]{c@{\quad}c}
            \verb+ \mathcal + & \verb+ \mathbcal + \\[6pt]
            \mathcal{Em} & \mathbcal{Ln}
            \end{array} \]%

        \end{document} 

If it is only about the caligraphic l (which you mentioned in the question), then you can use \ell. This is often used to avoid confusion between the letter l and the number 1. Remember that you have to use \boldsymbol{} to print (well..) bold symbols instead of \mathbf{}

\documentclass{article}
\usepackage{amsmath}
\begin{document}
    $1 \mathbf{1}  \quad  l \mathbf{l}  \quad  \ell \boldsymbol{\ell}$
\end{document}

If it is more general and not only about l, then see the question linked by @barbara beeton