This is the Kururin destop toy with a sand-couterweight-mod. On each end is a small hollow space. It has to be filled with fine quartz sand. After that fill out the small gaps with hot glue. It is important that there is no movement of the sand (shake it to check it). Then clean the surfaces with a sharp razor and finish it with 2mm foam rubber.
I have printed it with a 5mm brim and PLA