After the window mounted phone dock I bought online broke before I could even use it I decided to take things into my own hands and build a dock that integrates a little better with my car.
The previous owner of my MINI removed, or managed to break, the floating cup holder that mounts to the center column leaving just the mount. Because of it's convenient location and ease of integration I chose to use it as the base for my dock.
I know this seems like a fairly specific application and I admit it probably is but it should be pretty simple to use this overall design and just change the mounting method to something that works with your car. Innovate!

Step 1: Materials and Tools

Materials
* Aluminum Tube, 3/16 DIA X 12" L .
* 45° Angle Joint, and 90° Angle Joint . I could only find them in copper at the local hardware store but if you can find aluminum it should be cheaper. Depending on how you plan on attaching it to your dash you may need a different angle than 45.
* Popsicle (Craft) Sticks . Most any sort of light, thin, rigid material will do.
* Epoxy, Cement, and/or Pipe Solder . I used a general purpose silicon epoxy/glue and it seems to be working but I'll update if that changes.
* Phone Case. You must be able to get the phone out from the front of the case and obviously see the screen when the phone is in it. i used a silicone case which was cheep and available but it is floppy and non-stick which made the build a little more complicated than I had hoped.
* 2-3 Cable Ties .

Tools
* Ruler
* Hacksaw
* Knife

Step 2: Build the Frame

The first step is to get in your car and figure out where phone needs to be positioned and take measurements.
Cut the the tube, using a band saw if you can or being careful of crushing it in a vice or clamp, into 3 pieces:
A stub for connecting the mounting pin (MINI only) to the 45 angle.
A short (~2") piece used for the horizontal positioning.
A longer (4"-5") piece for the vertical support. This piece should be sized to fit your phone. I have an Evo which is pretty large, you may need a smaller piece.

Once the pieces are cut get back in the car, fit them together, and hold them where they will be mounted. Pay attention to the angle of the joints, one or both of them may need to be twisted to compensate for the angle of your dash or other mounting location.

If everything is the right length break out the epoxy. Give it sufficient time to setup completely. If you test it to soon the weight of the phone will cause your joints to twist.

Things to consider when deciding on placement:
1. Obviously, can you see it from the drivers seat?
2. Does it block the view of any instruments, the road, or even air vents?
3. Is it close enough to the outlet that you can plug in your charger?
4. Is it in the way of passengers or proper operation of the car?
5. Is it in front of an airbag? (If you answer yes don't drive until you fix it. Aluminum tube in the brain will ruin your or someone you love's day.)

Step 3: Attach the Case

Next attach the case to the frame using the cable ties.

Using an extra piece of tubing, or your frame if you don't have any extra, as a guide make 3 pairs of small incisions, parallel to the tube, in the back of the case. Each pair should have one cut on each side of the tube and should be as close to the tube as possible. Also try to make the cuts no bigger than the width of your cable ties, you want them snug.

Feed the ties through your cuts with the ends to the ties on the back side.

Position the frame on the case and tighten the cable ties. Leave them one or to clicks from fully tight so the angle of the case can be adjusted. Take the assembly out to your car, position the case to your liking and then tighten the ties as much as possible. Finally, trim the ends of the ties.

Step 4: Support the Case

Since the silicon case isn't rigid it will need some sort of support to keep it from flopping around wildly.
Simply cut your craft sticks to size (the width of the case), slide them between the frame and the case, spread as wide as possible, and epoxy in place.