Let visitors choose themes wordpess (theme switch)

I was wondering I made 2 themes one black, and one white. Now I would like to have visitors switch between the themes. All I can find are plugins that where developed a LONG time ago. Like this one: http://ift.tt/1QIJzjp

Does anyone know of a plugin or how to make your own (simple) theme switcher?

Thanks in advance!

Cheers.

via Chebli Mohamed