It is a numbers game like an hour glass.

The glass doors also get a residue that is hard to get off. 

The print has to be big enough for an old guy with glasses to read or it's a wasted mailer.

Then take an all glass avionics suite  3 axis fully coupled auto pilot..

Also of note, I am a glass is half-full guy so I tend to focus on what I can get done, not obstacles.  

•Mortgage Brokers (Lenders)•Real Estate Agents•Real Estate VendorsoTitle CompaniesoEscrow CompaniesoAttorneysoAccountantsoContractorsTermiteRoofingPlumbingAir ConditioningHeatingFloor CoveringElectricalSheetrockPaintingGarage DoorConcreteGlass/windowCabinetHandymanoHome InspectorsoHome WarrantyoPrinteroSign Companyo AppraiserThe most important conversation you will have with these vendors will also include a question regarding who they know who may need to buy or sell a house.Much like the conversation with the lender it will start by you introducing yourself and commending them on a positive trait or event.You: Dial NumberThem: Hello You: Hi this is (Your Name) I am calling for (person) Them: This is he.You: hi (person who referred you) suggested I call, I am looking for a (Trade) is that something you do?

The glass block windows I get from another place are made in their shop too.

A (rather pretty, I have to say) glass hash pipe fell onto the floor.

If you can't get a mailing address on there you're stuck with a bunch of cards the postal service won't mail out.In order to find that space I would restructure the first slide, which I assume is the back.

Use a reputable trusted marketer....Only other thing I can think of would be to slide a few of your own addresses in the mix and see if you receive the letters.