Long ago i made Ammobox for 5.56x45 NATO. https://www.printables.com/model/85281-sig-550-ammo-box-556-556x45mm-nato-strip ( I updated also this models)
Now you can have a Handle to Carry 3 Ammo boxes (150 rounds) or 6 or even more boxes /rounds.
The handle has a locking function with plastic spring.
To assemble it, you need a M3x8 Screw and an Voron /CNC Kitchen M3x5x4 Threaded Insert (M3x5mmx4mm). Like this.. [Affiliate Voron Design Link] https://www.google.com/url?q=https://s.click.aliexpress.com/e/_dW3Uprs&sa=D&source=editors&ust=1701974528946343&usg=AOvVaw3mgeoCtX48DK1wf7EoRCax
The author marked this model as their own original creation.