The one thing you make sure you do already have around for making a scratch body shape is your neck. That way you can precisely get scale length/bridge placement.......the most important aspect
It also allows you to look at the attachment area too......where you want the body wood to extend to, cutaways, etc etc.
For scale length I tend to measure to the 12th fret centre, then physically move the ruler measuring that same distance onward.
Orbital sanders and the flap-like sanding dics you can attach to 5" grinders make shaping a lot easier.
And new + quality router bits greatly reduce the amount of sanding on the sides and on the roundover.