Bolting storage box in back

I purchased a metal storage box to fit in the back, behind the front seats. Ideally I want it removable, some kind of quick-release bolts. Any ideas?

Cheers
Pete

Some sort of rubber strap maybe? Small bonnet strap?

Mine are in angle-iron 'rails' -



And then secured by the spare wheel -



Which is strapped in place on an angle so that I still see out of the back window...

Other ideas -

Wing nuts?
Or a ratchet strap between the two bottom rear seatbelt mounts - you can get eye bolts (with a ring on the top) with the correct thread (M12 metric fine 1.25mm pitch thread) to wind into them...

You'll notice in the second photo that I've taken all my internal rear trim out to make more storage space (around the roll cage) as you've asked in another thread...

Thanks, lookin' good. Wing nuts is a good option, forgot about those.

Place it length ways in the car and then fit a spacer(length of wood) between it and the door so it is tight enough to hold it in place.