How to wall while microing and macroing in fedual?

When I look back at replays, so much damage could've been prevented if I walled earlier or there wasn't a hole in the wall. But the thing is that walling takes so much apm and I might've already lost my scouts to enemy spears after I finish dragging out a long palisade wall. My macro might slip too. And I feel like I spend so much time thinking about where and how to wall my base (I'm bad at geometry I guess). Any tips on how to practice this and are there scenarios or tools that can help me learn walling?