There are also "proportional dividers" which can be set to automatically convert a photo or drawing divider setting to a larger or smaller proportion corresponding setting. Finding such old school equipment may be a challenge.
But with computers I have found that it is easier to use scanned in photos that can be adjusted (even some free drawing programs have perspective tools that can flatten an image) to use as a base layer over which you can draw in separate layers. Even if the photo is slightly in perspective you can count on one vertical strip to project vertical dimensions. Truck centers and other known horizontal dimensions can be used to landmark key elements.
