I had to cut some boxes in 3/8" T1-11 and I grabbed my biscuit jointer. It worked surprisingly well.
I did my lay out lines on 1 foot strips of blue painter tape in a tic tac toe pattern so they extended beyond the plate of the jointer and used the layout lines on the jointer to line up the blade. I did need to clean up the corners with a keyhole saw but the bulk of the cut was done and the hole was squared up.
Just be sure you hold the jointer tight so it doesn't walk.
