Allen Wrench, Allen Key, Hex Wrench, Hex Key…. Whatever you call them, these are the T-Handles for them. These T-Handles seem the be plentiful for metric sets but not for SAE sets. Sizes range from 0.050" to 3/8" (13 sizes).
This is specifically for an SAE set for the following sizes:
I printed with PLA, 0.4 nozzle, 0.2 layer heights, 4 Walls, 20% cubic infill, and a brim on the outside of the stem pieces.