A few years back, I made a little jig for cutting miters on small trim pieces using a pull saw. That jig worked well; but, was too narrow.....I needed more room to get my hand/fingers in there to hold the trim while I made the saw cut.
So, when the right scrap was available, I remade the jig.....
Note, I used the off-cut of the center piece to make two guide blocks for the initial forming of the miter slots and clamped them to the jig to make certain that they didn't move until that cut was completed.
Cool. I still use a crappy wood one from the big box store with my back saw. Never thought of a making one for a pull saw. Got to put this on the make list.