Sure, it’s possible to cut out your body shape with a handheld jigsaw.
But it might not look too great.
Or be quite square. Jigsaw blades aren’t that rigid, especially when you try to make them turn.
Router and template will be used to fix all that. Here’s the neck with position markers (MOP dots) inlaid.
(I later realized that I’d purchased larger 1/4″ dots especially for this neck, but I’d forgotten about them until I’d already inlaid all these 5mm dots. Oh well.)