A simple coffee tamper with a 6.2 cm diameter. It's made hollow to add extra weight, since tampers are metallic. I filled mine with metal BBs, but sand will work too. The print is divided into two parts that screw together.

I use this with my coffee filter holder when making slow drip cold brew coffee.

More on my website: https://souzoumaker.com/blog-1/2018/8/2/cold-drip-coffee-set