Locksmith - Mailshot

I have been given the profession of 'locksmith' and i am quite excited about it as i can immediately think of lots of imagery. I have to design and produce a business card, envelope and at least one other graphic device (such as a poster/postcard or promo leaflet etc) I want to create something simple and striking that has appropriate imagery and as another graphic device i want to use a promotional item that has a 'call to action' element in it that will make my mailshot an effective device.