Many hex drill bit holders are friction-based which make it difficult to remove/insert bits.
I got so annoyed so decided to design my own. Yikes, it took weeks (well, I'm still a novice) but here is a pretty good working holder. Bits are free-moving with my design and locks only when in closed position. There is also a window to show the stamped bit size which make it easy to select the correct size.

The body is designed to be multi-duplicated to become one piece of many bit pieces.
Use your slicer to duplicate on x-axis with zero gap to make the size you need.
On ideaMaker slicer this function is listed under Edit-Array. Put the number of bits you need in X_Count, zero for X_Space, 1 for Y_Count.
Other slicer have functions like DUPLICATE, COPY/PASTE, or ARRANGE. Just use zero width with them, but none of them work as well as ideaMaker slicer.
It is not the best slicer, but ideaMaker works well for array duplication. You can then export it back to your own slicer.
Or, just use the STEP file to make your own duplicated bodies.

It is a bit tight to match the front and rear parts. Normal plastic wear makes the fit better. Make sure there are no debris between them.

Insert a filament or steel rod in the hinge hole to connect the front and rear parts.
You may have to lubricate the filament first for easier insertion. Steel rod helps in any case to clear out any debris in the hole first.

Use PLA or PLA+ for accuracy. Dimension may have to be adjusted for others with different shrinkage.
I used 20% infill, 2 shells, 0.15mm layer height.
No support should be needed.

Update: Added a base to hold the holders. The rear part was modified slightly to prevent slipping off the base. The base does not have to be the same width as the bit holders.