I use a 6" Sawzall blade in my jigsaw to cut the outlines then a railrunner to square it up, or a hard block with sandpaper. (We have plastic Rail Runners for less cost as well)
Do you still use a jigsaw and your homemade blade to cut outlines? I cut down the saw blade from a reciprocating saw to use in my jigsaw but tends to deform the cut a bit. It's hard to find a blade that is stiff enough to cut accurately.