Materials:
Skateboard Wheels with Bearings x 16
Aluminium Angle (2"x2") x 4
Wooden Board x 2 (same size)
Nuts & Bolts x 16
Larger Nuts & Bolts x 4
Plastic/Metal Caps x 4
PVC Piping
Tools:
Drill
Spanner
Saw
INSTRUCTIONS
These instructions will explain the basic concept of building your own dolly. There are no measurements or dimensions for the track (pipes) or board as it really a question of building with whatever you can find and, most importantly, what will be useful to you.
The diagrams pretty much explain themselves but for those who prefer the written word, keep on reading.
Figure #1 shows how the skateboard wheels, bearings, nuts and bolts and finally the aluminium angle all fit together.
Each aluminium angle should have four wheels attached to it (two either side). The aluminium angle will require holes to be drilled into it and the length of it should be long enough to comfortably fit two wheels placed side-by-side on it.
The holes should be drilled at either end which then a bolt will run through and secure the skateboard wheel to it (see Figure #3 for alternate angle). An additional hole needs to be drilled in the join, dead centre. This is where another bolt running through the boards will join the angles.
Once you have prepared four of these angles, you need to find two pieces of wood sturdy and big enough to hold your camcorder tripod (and the camcorder of course!).
You can nail or screw the two pieces of wood together. The reason you are using two pieces of wood rather than just one thick piece is for added stability and to prevent "bowing" caused by the load upon it.
With the two pieces of board fixed together, now attach your completed aluminium angles to the corners, ensuring to line them up correctly. Note: If the angles aren't lined up correctly your dolly may either bend the tracks once being pushed or worse - fall off smashing your camcorder!
You will need to drill holes through the boards into which the longer bolts will run through straight into the hole in the angle which was made in the centre (Figure #3). Do not secure these bolts with a nut. They need to be able to rotate freely as this will allow the unit to compensate for less-than-straight pipe tracks.
The last bit is to attach four caps (plastic or metal) to the main platform. The "caps" are going to act as holders for your camcorders tripod so find caps that will fit snuggly. They aren't essential to the construction but don't be surprised if without them your tripod slides off mid-shot.
Then that should be it! Of course you still need to lay your tracks which is where the PVC piping will come into play. Just remember that the tracks should be the same width as you have made your dolly platform so you may need to get out the old tape-measure.
Hints & Tips
The tracks should ideally be laid onto level, even ground. Even a few pebbles in the way can cause wobbly footage so be careful.
If you require a long track run (over 2 meters) cut your PVC piping into 2 meter sections and then piece them together using strong tape. Why? It makes it easier to transport!
Do several test runs of the track to test stability. Film some footage, review it and make adjustments accordingly.
Remember, this isn't a professional level dolly so standing or sitting on the platform will most likely destroy it. You may also still need to keep your image stabiliser on (unless you find the run is silky smooth then turn it off!)
If it helps, construct a handle to push the dolly along (see diagrams). Construct it out of whatever you can find that will do the job.
GOOD LUCK! 
REFERENCE
Tags: CAMERA DOLLY TRACK HOW TO
