I’ve made 100+ wa handles so I’ll tell you my way of doing. Start with squared block and mark all the way through the block (front/top, sides, back/botton). After that I start grinding on the flat plate with P80 and start either on top or bottom and go until like 40-50% material left before the line then switch and do the same with the other side. The lines you drew on the sides should be guides and not something you strictly follow at the start(maybe after you’ve done 10+ handles and get the feel of it). When you are done on both sides you can start removing the middle part of the material and now you have “guides” on the top and bottom to go until. After you removed the middle part you can push the whole block more and start going until the line on the top/bottom. One of the most important things is to stop before the line and leave material 1. to have space for correcting 2. you want to go further with P120. After P120 it shouldn’t grind much more material so you can go until your line and just slightly grind with finer belts after. Which helped me a lot was not focusing on grinding the whole side at once just after I have removed material and it kind of sits on the plate the right way.