[FoleyEngineer]

We've cut large sheets of lexan and aluminum with a jig saw and a fence and it has worked very well. Tips:

1) Clamp the fence and workpiece to a table as close as possible to the edge.
2) If possible, add a second table to support the piece being cut off and clamp a fence to that also that that your jigsaw rides between two rails that keep it straight and true.
3) If your jigsaw has an orbital mode, use that (blade moves in circular forward/back path instead of only straight up and down)
4) If your jigsaw has a knob on the top that allows you to turn it for curves and it can be locked down, do so.
5) Use a metal cutting blade. If you notice your noise going up after a while and your chips and forward progress decreasing, toss it out and put in a fresh one.
6) Move at the best speed that gives you nice sized chips and doesn't stall the motor. Too slow is as bad as too fast. Experiment.
7) Use a shop-vac held by an assistant to suck up the chips and give you a clear view of your cut-line and progress.
8) Keep downward pressure on the jigsaw. You don't want it "chattering" and bouncing upward as the blade completes its downstroke.

That's all that comes to mind. Good luck!
John