One of the things that our team has made routine is what we call double drilling our Tetrix channel. We repeat the standard hole pattern where it isnt to give us more mounting options and general mounting flexibility. We have found that it doesn't weaken the channel in to a noticeable factor. The bottom piece in this picture is what the channel started out and the top shows the holes we added. It all matches the same pattern, to keep modularity and reusability.
Step 1: Supplies
1. a piece of channel to double drill
2. a Tetrix flat plate
3. two screws and nuts
1. Drill (preferably a drill press)
2. 9/64 drill bit
3. alan key to tighten screws
Step 2: Set Up Jig
Step 3: Drill!
We have found that it is usually only necessary to drill the holes into a + shape, rather than the full "flower pattern."