Cord stop for all your drawstring needs. Fully 3D printable, including the spring mechanism. 5mm hole works well with shoelaces or similar. Fusion 360 file included with customizable parameters so you can change the hole size (and some other measurements) if needed.

Add a dab of superglue to the bottom end of the plastic spring before inserting it into the outer casing if you want it to stay in place even when the cord is removed.

Highly recommend printing in PETG. PLA will work but the spring will need replacing much sooner.