So here is a thought for your grand opening that will tie in the safe and vault.
So the assumption is that you know the combination of the safe. If you don't then this plan is fck'd from the beginning, but assuming you do
First pull together some cigars and swag (but no Carlos Torano the Vault cigars, they are crap). Then place all that in the safe, close and lock. You can tease people with what might be in there but I wouldn't give them the details
You create, lets say, 100 safe combinations, 99 are fake, 1 is real. Each is placed in a small envelope and those envelopes are in a container of some kind, a box, a jar or pinned to a board. But use small envelopes with just small strips of paper with the combinations on them. Easier to manage.
Then you decide that for each customer who buys something, they get to pick an envelope with a combination in it and try opening the safe. Pick the right one, you win the contents.
Now depending on how you want to give out the combinations and the amount of foot traffic you may need to adjust the number you create. Just make sure you tell them once the combinations are gone then they are gone, once the safe is opened the contest is done. Maybe if they don't pick the winning combination you give them a prize. Like 10% off their next purchase (creates repeat traffic) or some cheap cutter with the B&M logo/name
Suggestions or a couple of examples, using cigars or $ spent.
By 3 cigars get 1 envelope
By 5 cigars get 2
Buy a box get?
Spend $25 get 1 one envelope
Spend $50 get 3
Spend 100 get ?...