First, get a block of oak
And after awhile, you wind up with a wood bodied edge plane. Almost a skewed Rebate plane. Say this being built on a youtube show from China. Any way, here we goNot too bad a start? The cutter at one time was an old Harbour Freight Skew Chisel for a lathe. Reround the edge to match the plane's opening. Wedge was another chunk of oak, more on the later. Saw cuts: These are at 45 degrees for the bed of the cutter. BUT, it is also a skewed cut, as the outside edge is skewed towards the rear. about like that. Meant the cutter needed ground to match. Cutter is about 1" wide, and 1/8" thick. Once I got the iron to seat just right, I fitted the wedge. Then set the wedge aside for awhile. There is an escapement ahead of the cutter. To make the "Mouse Hole" as the OP puts it..a) he used a gouge of about the right sized sweep. b) having no such tool in the shop, I wound up using a 1/4" wide chisel and chopped the hole. This changed the wat the wedge fit.. Wedge has so many compound curves in it. Got the "normal" angle, and it was skewed to boot. Then a bevel was ground onto that, for the shvaings to go out the side. Thatbig knob on it's top was removed as well, too hard to tap the cutter with that in the way.
I said edge plane, right. Well that means a fence for along the bottom Had some oak about the right thickness, and cut to length. Well actually, I made two of them. The idea is that two bolts go up through the fence and into a pair of square nuts. Fun. Here is a pair of holes, the cutter, a wedge, and the nuts and bolts. I drilled through the fence and into the sole of the plane, on the side away from the cutter. Drilled a second pair of holes into the fence, only. Then drew a line or two to define a slot. Had the slots almost done and chiseled out, when SNAP. I lost one end of the fence, now I remeber why I made two. Instead of a chisel to make the slots, a forstner bit the correct size was usedabout like that. Not worried about the bolt heads sticking down, as they aren't to touch anyway. One othe little chose to do. There needed to be a shallow notch chiseled out to clear the cutter when making narrow rebates. And since I was in a carve mood, the top of the body got a little work done too. Four shallow saw cuts, at 45 degrees to the nose, were made down near the toe. One set was a hair deeper than the front ones. Big old chisel to hack away the waste, leaving a step up frontOk, so where is the rest of the story?