Stackable trays / holders. One designed for socket 7 CPUs, so compatible with socket 5/370/A also, other intended for 486 processors. Can be comfortably hold, see photos.
Fits smaller beds, with dimensions 157,4x157,4mm it can be printed on my humble Ender 2 Pro.
Can be bought at 1701.cz :)
The author marked this model as their own original creation.