How can I word this... Diaper raffle invite?

So I'm having a drop in baby shower because the building we rented has a 75 seating limit, but we're inviting 100 or so people. I want to have a dialer raffle but since people can't stay the whole time for the raffle what should I do? Should I just word it differently and instead of having a raffle ask for a few diapers if they would like to bring some?