Holster for nanovna on multiboard.
https://www.multiboard.io/
You'll need either a pair of multipoints or a rail to place it on, whole thing lifts off easily when you need to remove it.
SMA plugs stick out the bottom with space for the protective covers it came with so when it's set down on a flat service the VNA pops up slightly.
The author marked this model as their own original creation.