The M-85 flash grenade is a Toy/prop featuring a hollow inside for storage.
Makes for a good prop or decoration for military enthusiasts or, if you need a flash for an airsoft field.
The assembly is easy and it requires no tools I hope.
You will need a 1mm pin to hold the striker in place and a torsion spring to make it actuate.
I recommend printing this project 1 piece at a time.