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I measured the clearance in the box and went slightly less so that using the box strop would hit the edge

I used tape to get the angle the same as the box honing system, and just stuck a whittled down chop stick in the hole

I used a cut down chop stick. You still need the finger push as the chop stick is not in there very securely, but the stick helps you flip. That's how I will do it again.

I've heard of people replacing the stone with hardwood of the proper thickness and 1um lapping film.