[Tex/LaTex] Tabular with horizontal and vertical double line, avoid ugly corner

Question

I am using tabular to make simple table, I want to have double line on the sides. The problem is that the double-lines do not meet elegantly at the bottom-right corner:

How can I make the double lines meet in a better what (e.g. forming an double ell shape)?

Other environments and packages are welcomed but tabular is preferred.

Minimal code:

\documentclass[]{article}
\usepackage{array}
\begin{document}
\begin{tabular}{c|c||}
1 & 2 \\
3 & 4 \\
\hline\hline
\end{tabular}
\end{document}

Answer 1

As mentioned in the comment by Johannes, vertical rules should be avoided. You should use the package booktabs to create nice tables.

However David Carlisle created the package hhline which supports such requests.

\documentclass[]{article}
\usepackage{array,hhline}
\begin{document}
\begin{tabular}{c|c||}
1 & 2 \\
3 & 4 \\
 \hhline{=:=:b|}
\end{tabular}
\end{document}