2. Make templates out of ordinary (square) paper for the cam plate and post plate, with marks
where to drill, and glue it with a paper glue stick on the aluminum bars. When you need
to remove the paper, some plain water will dissolve the glue and it will easilly come
off.
3. For the cam plate, you need to drill one 6.5 mm hole for the camera screw and then
countersink it. Then, to cut the notch drill several holes just next to each other.
Since the notch should be just as wide as the square neck bolt (6 mm), make sure you
use a smaller drill (4-5 mm) and file up the rest of the notch using a small metal file
or a Dremel type of tool. Aluminum is fairly soft, so it's easy - but can take quite some
time.
4. For the post plate, drill and countersink two 4 mm holes, then drill holes for the notch - as with the cam plate - and complete it using a metal file.