There is no way I'm spending $40 or more for a device that has to be babied and can't be used in adverse weather, so I chose to build one of these instead, as they are better suited to the outdoor foul weather use that a GoPro camera can be used in. After pulling the sprinkler timer apart, the internals are indeed either plastic, stainless, or coated steel with an o-ring to help keep most moisture at bay. The final product is compact, robust, and exactly what I was hoping for.
UPDATE: This is a first rough outing with a Canon Rebel DSLR on it, 2 second intervals run at 30fps. On the right track, a little tweaking to figure out still.
UPDATE 10-27-13: First attempt with a GoPro. I hung the timer inverted off a jib so the rotation would go left to right.
Step 1: Timer Modifications
Next is to remove the yellow cap containing the timer mechanism from the gray valve body. In this model, it snaps in at the factory and is simply not designed to be removed without some bit of destruction. If you look carefully in one of the holes left behind from the removed hose connectors, you will see a vertical plastic block inside - this is where the locking stem from the yellow top cap is clipped into. Taking a small drill bit I carefully drilled a slot until I hit the locking post inside. Taking a tiny seal puller or hooked awl, I snagged the latch and PULLED IT TOWARDS ME, releasing the locking post and allowing the yellow timer cap to be removed.
At this point you have now a separate yellow top with timer inside, and the gray bottom valve body.
Step 2: Remove Timer Mechanism / Install Camera Mounting Bolt
You will see they thoughtfully molded a guide into the yellow cap for drilling. After drilling the hole, grind that ring down flat - you need every millimeter of clearance between the bolt and the timer.
NOTE!!!Use a counter-sink flat head type bolt rather than the one in the picture. It stuck up a bit too far and had to be ground to fit it back together properly.
Bolt the 1/4" x 20 screw into the cap and tighten. A thread locking compound is added assurance that they won't loosen, as re-tightening will require dis-assembly to reach the screw head..
Step 3: Insert Tripod Mount Into Base
Again the manufacturer has provided a guide for drilling, but be careful, as internal structures will push your bit off center as you go through the bottom. Fine tune the hole so that the "grippers" on the insert have some plastic to bite into.
Mixing up a batch of the epoxy, I put some in the hole and around the edges, then hammered the 1/4" x 20 Insert Nut in flush. That's all there is to it.
Step 4: Final Assembly
Lastly, I wrapped the body of the timer with electrical tape - an innertube from a mountain bike tire would have been better - but none laying around, so the tape it was.
As always, comments and suggestions are always welcome. Happy trails.