This will hold an SFIC core perfectly with or without the control key. If you have the control key use one side and if you don't just turn it around and the
...Plus control bar will hold the core in place with friction. It will wear down over time and become less tight but it's still suitable for picking.
Lock sits flush with the face of the holder and it works with 5 to 7 pin SFIC cores.
I have printed this and it works perfectly.
Version7 fixed the STL orientation so that no editing is required to print the part.