Cite in text with slashes between authors in author-year style

Question

I am trying to cite my reference with the following structure

author a/author b/author c, year

with slashes and without spaces between the authors in the author year style. You can find a MWE below. As a precaution, I have included all commands related to my bibliography in case there might be somecomplications with the already existing changes.

\documentclass[article, bibtotocnumbered,liststotoc,12pt]{scrartcl}
\usepackage[T1]{fontenc}
\usepackage[latin1]{inputenc}
\usepackage[ngerman]{babel}
\usepackage[paper=a4paper,left=50mm,right=20mm,top=20mm,bottom=20mm]{geometry} %define margins..
\geometry{a4paper} 
\usepackage{lmodern}


\usepackage{filecontents}

%Bibliotheken
\usepackage
[style=ext-authoryear,labelnumber, useprefix=true,
sorting=nyt,maxbibnames=9,maxcitenames=3,uniquelist=false, backend=biber, 
doi=false,isbn=false,url=false,
uniquename=false,bibencoding=utf8, date=year, giveninits=true, terseinits=false, dashed=false]
{biblatex}


%Remove Dot after volume
\renewbibmacro*{volume+number+eid}{%
  \printfield{volume}%
%  \setunit*{\adddot}% DELETED
 % \setunit*{\addnbspace}% NEW (optional); there's also \addnbthinspace
  \printfield{number}%
  \setunit{\addcomma\space}%
  \printfield{eid}}
\DeclareFieldFormat[article]{number}{\mkbibparens{#1}}

% Number of articles in parentheses
\DeclareFieldFormat[article]{number}{\mkbibparens{#1}}

%Dot after journal title
\DeclareFieldFormat{journaltitle}{{#1}\isdot}

\renewbibmacro*{journal+issuetitle}{%
  \usebibmacro{journal}%
  \setunit*{\addcomma\space}%
  \iffieldundef{series}
    {}
    {\newunit
     \printfield{series}%
     \setunit{\addspace}}%
  \usebibmacro{volume+number+eid}%
  \setunit{\addspace}%
  \usebibmacro{issue+date}%
  \setunit{\addcolon\space}%
  \usebibmacro{issue}%
  \newunit}


%Dort und Sorting Last-First
\DeclareNameAlias{sortname}{first-last-bold}

\DeclareNameFormat{first-last-bold}{\mkbibbold{%
  \ifgiveninits
    {\usebibmacro{name:last-first}{\namepartfamily}{\namepartgiveni}{\namepartprefix}{\namepartsuffix}}
    {\usebibmacro{name:last-first}{\namepartfamily}{\namepartgiven}{\namepartprefix}{\namepartsuffix}}%
  \usebibmacro{name:andothers}}}


\begin{filecontents}{\jobname2.bib}
@Article{Hansen2011,
  author  = {Hansen, Peter R. and Lunde, Asger and Nason, James M.},
  title   = {The Model Confidence Set},
  journal = {Econometrica},
  year    = {2011},
  volume  = {79},
  number  = {2},
  pages   = {453-497},
  url     = {https://EconPapers.repec.org/RePEc:ecm:emetrp:v:79:y:2011:i:2:p:453-497},
}

\end{filecontents}
\addbibresource{\jobname2.bib} 

\begin{document}
\textcite{Hansen2011}
\printbibliography
\end{document}

Answer 1

With

\DeclareDelimFormat{multinamedelim}{\addslash}
\DeclareDelimAlias{finalnamedelim}{multinamedelim}

you turn the delimiters to slashes in all contexts. With

\DeclareDelimFormat[bib,biblist]{multinamedelim}{\addcomma\space}
\DeclareDelimFormat[bib,biblist]{finalnamedelim}{%
  \ifnumgreater{\value{liststop}}{2}{\finalandcomma}{}%
  \addspace\bibstring{and}\space}

you get back commas and "and" in the bibliography.

Here is a modernised version of your MWE that makes use of biblatex-ext features (\volnumdelim and \jourvoldelim) as well as features new to biblatex 3.12 (\DeclareNameWrapperFormat) to achieve the same output more elegantly.

\documentclass[12pt, bibliography=totocnumbered, listof=totoc]{scrartcl}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}% UTF-8 is the usual encoding in modern editors,
                           % it's even the default for modern LaTeX versions
\usepackage{lmodern}
\usepackage[ngerman]{babel}
\usepackage{csquotes}


\usepackage[backend=biber, style=ext-authoryear,
  maxbibnames=9, maxcitenames=3, uniquelist=false, uniquename=false,
  useprefix=true, giveninits=true, dashed=false
  doi=false,isbn=false,url=false,
  date=year]{biblatex}

\DeclareNameAlias{sortname}{family-given}
\DeclareNameWrapperFormat{sortname}{\mkbibbold{#1}}

\DeclareDelimFormat{multinamedelim}{\addslash}
\DeclareDelimAlias{finalnamedelim}{multinamedelim}

\DeclareDelimFormat[bib,biblist]{multinamedelim}{\addcomma\space}
\DeclareDelimFormat[bib,biblist]{finalnamedelim}{%
  \ifnumgreater{\value{liststop}}{2}{\finalandcomma}{}%
  \addspace\bibstring{and}\space}

\DeclareFieldFormat{journaltitle}{#1\isdot}
\renewcommand*{\volnumdelim}{}
\DeclareFieldFormat[article]{number}{\mkbibparens{#1}}

\renewcommand*{\jourvoldelim}{\addcomma\space}

\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@Article{Hansen2011,
  author  = {Hansen, Peter R. and Lunde, Asger and Nason, James M.},
  title   = {The Model Confidence Set},
  journal = {Econometrica},
  year    = {2011},
  volume  = {79},
  number  = {2},
  pages   = {453-497},
  url     = {https://EconPapers.repec.org/RePEc:ecm:emetrp:v:79:y:2011:i:2:p:453-497},
}

\end{filecontents}
\addbibresource{\jobname.bib} 

\begin{document}
\textcite{Hansen2011}
\printbibliography
\end{document}