MediaWiki templates/infoboxes

I’m almost done building a wiki for one of my domains, with one exception. I am terrible at designing templates and infoboxes. Does anyone know of any graphical tools to build these (mediawiki or firefox extensions)? There are plenty of WYSIWYG editors for basic wiki markup, but I can’t find anything for infoboxes and the like.

I don’t know of the best way to do what your asking.
But, as for helping design.
Try using the firebug plugin in firefox.

It will allow you to view changes your going to do, before implementing it.