Step one: Make a plan. I usually skip this step, with the predictable results. When I do make a plan, I usually use a CAD package but this time, I just sketched it out. I just winged it for the the lengths and angles, based on Bill Carter’s planes and planes I have. I wanted low angle (I wound up with 15 degrees) to give a block plane like feel.
The basics are here, angles, lengths, where the wood goes, where the tabs are and the shape.
Note: This is basically a sketch (duh) and was modified on the fly, as you can see from the scan.