Art stores sell a soft wood Burnishing Tool. This tool has a flat side, round side, and has a geometric shape at the opposite end. It is designed for many types of foils and acrylics. I use mine to death since I'm a Rub -n-Buff fanatic and use a lot of gold and copper foils that I rub out to change the hue. These tools are easy to make out of Basewood.
I also still use toothpaste as a polishing agent. Kinda old remedy but is cheap and plentyful.