How to Cut a Long Extrusion Lengthwise?

[Just puttering]

Cut the leeding edge? The cut will not need to be as precise and some deformity in the front is probably better than the rear

If you did this you may be able to cut it with a sharp blade

[Hobby Racer]

How about a Dremel table with a cutoff wheel. Those things are pretty thin.

I am also looking at this option, but it would require a very steady hand to make a straight 4ft. cut!

A little late to the party, but 2 more cents: The bandsaw blade idea is great as long as you can rig it up TIGHT. Your hot-wire idea is good, too. The only other way I can think of using common tools would only work if you can get a second airfoil. You could mark your line and rough-cut on both ends with a grinder, then sand to your line and bond the two halves together around the bar.

Yes, I'm still thinking about how to rig the blade up really tight. I want to only cut one half so the there is no alignment issues. By cutting only the trailing edge, the foil snaps around the bar like a clamp and keeps its shape well.

Cut the leeding edge? The cut will not need to be as precise and some deformity in the front is probably better than the rear

If you did this you may be able to cut it with a sharp blade

The foil is a hard ABS plastic and would not cut with a sharp blade. I thought about cutting the leading edge, and I may still do that if I can't cut the trailing edge well enough. Luckily I have another piece if I screw up!