Try peeling the paper off the back of it and sticking it on.
Thats what every Condo Assoc. with nice facilities is doing these days. You have to do it not only to prevent theft or damage, but to keep people out who are not living there. I would go with the code idea and give it out to each head of household. Change the code every month. If you give condo board heads keys to hand out when needed you are giving them to much power and could cause some irritation.