Temporary on arrival visa for visiting Macau

I have a South African passport. I am staying a few days in Hong Kong and then Travelling to Guangzhou where I will be staying a few more days (I have a single entry), then will be heading back to Hong Kong 24hour layover before flying back to South Africa. I would like to visit Macau during my few days, would I be able to obtain visa somewhere in China and Hong Kong to visit Macau for a day?