I recently bought a new camera for SCUBA diving and I decided to save some money on a lighting rig.

I didn't want to pay big bucks to buy a specific arm for my camera and light so I put something together out of PVC. I am using 3/4 inch pvc because that is what I had, but I'm sure 1/2 inch would probably be just as strong and more compact.

UPDATE - I just got some great input from a friend - a mix of 1/2 and 3/4 inch pipe may provide a good opportunity to make this set-up collapsible .

Step 1: Parts List

I wanted to make the angle of the light adjustable as much as possible when under water so I used threaded connections where appropriate. I also had to improvise on one part and use a couple of different junctions where you might get lucky and find the right part and eliminate a couple of the adapters. Also make sure all of these parts are Schedule 40 PVC and NOT FOAM CORE (this will eliminate problems at depth)

You will need:

1 - 1.5 inch 1/4 inch course threaded bolt. (I used Aluminum to avoid deterioration)
1 - male threaded plug
2 - 90 degree elbows. 1 end female threaded, 1 end female slip
3 - couplings. 1 end male threaded, 1 end female slip
1 - 45 degree coupling. both ends female slip
1 - coupling. both ends female threaded
1 - end plug. male slip
1 - length of pvc. I used about 3 feet but you will modify to fit your needs.
1 - hose clamp (big enough to go around a good mount point on your light.)

pvc cement
A drill (3/16 inch drill bit)
Screwdriver
a rotary tool to cut a slit in the light mount plug

-UPDATE- just a note, keep in mind that PVC is somewhat negatively buoyant... ok, carry on...

Step 2: Housing Mount

Take the threaded male plug and drill a 3/16 inch hole through the center. Screw the bolt in so that the PVC threads face down and the bolt threads stick out slightly through the top so you can screw it into your enclosure.

-ANOTHER UPDATE- I like the idea of having a rubber gasket between the PVC and the housing. I am testing screwing in the bolt all the way and putting a rubber hose gasket between the housing and the plug. Seems to work ok and provides good friction for adjusting left and right.

Step 3: The Light Mount

Take the slip plug and use your rotary tool to cut slits on opposite sides at the base of the plug so you can thread the hose clamp through it. Attach the clamp and plug to the light like in the picture (firmly but not enough to break your light!). I like this placement because it keeps the weight centered, keeps the plug mostly out of the way when I'm just using it as a light, and the rubber provides good gription so it doesn't slip!

Note - I chose a slip plug here because I do a lot of shore diving so I can easily pull the light off for easy entry and exit but under water there is enough friction to allow me to swivel the light - A threaded plug here might make sense for you.

Step 4: Assemble the Rest

Put the rest of the pieces together as shown in the picture. I know that this arm is probably WAY TOO BIG, but I only cemented one side of each of the long lengths of PVC because I still need to do some testing with my light underwater. This means I can pull those lengths apart and trim them down as necessary for my light and camera combo.

Step 5: Drain Hole!

You don't want this making a vacuum under water so I chose to put a drain hole directly under the camera plug. Anywhere else in the tube would work as well :)

Also I got paranoid and added a VERY SMALL air hole next to where I screwed in the bolt for the camera mount to allow air/water flow just in case. Check your arm to make sure there aren't any chambers that I missed...