How to (safely) measure the surface area of a human body? Here's a question just for curiosity.
You measure mass on scales.  You could measure volume by submerging in a bath with a snorkel system.  But how could you measure a living human's surface area without harming.
Ideas so far:
Using software to make a 3D model from images.  Effective, but very high-tech.
Wearing a morph suit and rolling in burrs until completely coated, then working out how many were picked up.
Standing naked in a room of known volume for a set amount of time and recording the temperature change in the room.  Would rely on knowing that the skin was uniformly at 37 degrees - could you reliably ensure this?
Preferable solutions would be simpler to implement even if a bit approximate.
 A: fun question. 
(Find a candidate;) take a given volume $V$ of honey (or paint, or anything dense, sticky and safe enough); cover the body with it; measure a mean thickness $h$ of the film around the body (take as many points as needed around the body); measure  the volume $V_o$ of honey left in the jar, ($V-V_o$ is the volume used); the approx. surface of the body is $(V-V_o)/h$ 
A: Using a measuring tape, measure the circumference of the person at as many points as you see fit. Try to space your measurements evenly.
The total area is the sum of all the circumferences times the average spacing between them. This will get your quite close to the right answer - certainly better than the "coat the subject in honey" answer which is fraught with experimental uncertainty.
You might separately calculate the area of the head (approximate the head as an ellipsoid, and compute the area. Then subtract the area of the cross section of the neck).
I expect you can get to better than 10% with this method. Clearly a full 3D laser profilometry measurement will do much better, but would be hard to perform with "readily available instruments".
