I recently purchased an Epson projector for home theater. I searched around and found that projector ceiling mounts are pretty expansive. I decided to make one myself. The total cost is less than $15.

Material:
From Homedepot:
1. LDR Industries 1/2 in. Black Iron Floor Flange, Model # 310 F-12, Store SKU # 817902
$4.27
2. Mueller Global 1/2 in. x 8 in. Galvanized Steel Nipple, Model # 563-080HN,Store SKU # 182540
$3.26
3. E-Z Ancor Twist-N-Lock 75 #8 x 1-1/4 in. Zinc-Plated Nylon Flat Head Phillips Drywall Anchors with Screws (4-Pack), Model # 11364, Store SKU # 892428
$1.49
4. Crown Bolt M5-0.8 x 16 mm Zinc-Plated Pan-Head Phillips Drive Machine Screws (3-Pieces), Model # 80138, Store SKU # 574498
$0.78

From SouthCo:
1. Constant Torque Position Control Hinges, ST-11A-200FA-50. You can request free samples.

Others:
~10cm thick,30mmx30mm scrap plastic or wood.
A piece of screw plastic or metal sheet that is big enough to cover the mounting holes of your projector

Tools:
hand saw, hand drill, M5 screw nuts.

Step 1: Procedure

1. Down load the projector layout & CAD Drawings from the manufacture website to find out the mounting hole positions or measure the hole positions your self. Mark down the holes on a piece of rigid plastic or metal board. Drill holes and mount the board to the projector. Add some spacers between the board and the projector. Trim the board as small as possible to avoid blocking the heat from the projector. The board I use is a piece of 3mm thick FR-4 board.
2. Drill two holes on one end of the pipe to mount the hinge.
3. Drill two holes on the middle of the mount board and mount the hinge to the board. Put a ~10mm plastic block in middle so the pipe won't hit the mount board when the hinge rotates.
4. Install the pipe to the floor flange. Hold the whole thing under the ceiling. Turn on the projector, Adjust the angel of the hinge for the Y position and adjust the distance between the screen and projector. Mark down the mount hole position of the flange on the ceiling.
5.Uninstall the flange, use drywall anchors and screws to mount the flange on ceiling. Put the projector back on the flange.

Now the ceiling mount is finished. You can adjust the angle of the hinge and rotate the pipe a little bit to adjust the image position on the screen.