I found this deburring tool (Burraway by Cogsdill) and ended up buying a 1/8″ (3.2mm) and a 5/32″ (4mm) from eBay for about $35 each. I wish I found this earlier. Basically it deburs the front and back of a hole with one simple operation with only access to one side of the hole. As you insert the tool into the hole the cutter deburs the front of the hole then as you push the cutter collapses and slips through the hole. As you pull back the cutter now deburs the other side of the hole and then it collapses and the tool comes out of the hole. This is great for deburring the channel type parts where you can’t get the normal deburring tool in the back or if you have to ream a hole or two in an area that you can’t get to the back and you’ve already riveted things together. The tools works really well, though if its a big burr you need to go a bit slow to make sure it removes all the burr. Eventually the cutter will wear out and will need to be replaced, but it should be good for a few thousand holes.