A gridfinity base for the excellent rotary vice by MikleVV. Magnets glued to the bottom makes it really sturdy, even for the most aggressive desoldering jobs.
Download the other STL-files from https://www.thingiverse.com/thing:6333559 and replace holder_bottom.stl with my STL.
I usually release the source file for stuff, but this was such a messy hack job that I'm too ashamed.
The author remixed this model.
I wanted a more solid base for the vise, and didn't need a sponge holder, so I whipped up a Gridfinity 1x3 base for it. Really solid with magnets glued to the bottom.