Box for table tennis ball

Funny box for table tennis ball(s), I've added two versions of an extender. One with seperator, one without. For the thread I've used threadlib, but with own parameters.
The feets do not fit exactly when it is closed. But this is difficult in any case, because it depends how strong you close it.
This is for 40 mm balls! It is designed for harsh environments, such as school bags ;-).