Step 1: The Stuff I Used
1. A Plastic Folder
2. A Craft Cutter or anything you could use as a blade
4. Pencil and Ruler
you'll also need some Super Glue and scrap paper that we'll use to cut out the template, I used an old flyer I found lying around the house.
and of course the Garmin unit :D
Step 2: Make a Template
1. Place the unit on the paper and mark out where you'll be folding
2. Also mark the excess, which we'll be cutting off later
3. the visor is about the same length as the height of the unit, dunno if thats a right way of doing it but hey it worked for me :D
Step 3: Transfer the Template to the Plastic Folder
I scored the fold lines with the back of the cutter blade so I can fold them easier.
UPDATE: This isn't the final design, I eventually cut-out another one with a "bar" of plastic where the holder was to go, this serves to hold the visor in place when I lock in the unit to the cradle on the windshield.
Then just used some Super Glue to side the sides to the top of the visor, let it dry
Step 4: Access Holes
Step 5: Final Assembly
I'll eventually paint this black maybe but as it is, it works well to block out the sun and I can see my screen all throughout the drive.
Hope this helps fellow road travelers and GPS users like me.