Shape the handles clamped together so they end up the same size/shape. And just hack bits off with a knife & rasp until I’m happy with the final shape. Onto the crossbar, much the same process. Put it together to see how it looks.
Next up is the whorl, chop another piece out of the birch. And cut the mortice. Shape the curve and cut off the waste. Measure up for the toggle. Everything is more or less done. The toggle looks way too chunky so I’ll have to reshape that, and the brass plate I added to the end of the handles to reduce friction and protect the handle works far too well, not my brightest idea, so I’ll need to make some leather washers to go between them and the handle to stop things from slipping.
That’s my smallest coffin plane at about 3 ¼ inches long, works great for bevelling small pieces. The leather washers work, can cut curves without the frame swinging about now. And that’s it, should get more of a contrast between the apple and birch as they darken over time.